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GenBank® (https://www.ncbi.nlm.nih.gov/genbank/) is a comprehensive, public data repository that contains 34 trillion base pairs from over 4.7 billion nucleotide sequences for 581 000 formally described species. Daily data exchange with the European Nucleotide Archive and the DNA Data Bank of Japan ensures worldwide coverage. We summarize the content of the database in 2025 and recent updates such as accelerated processing of influenza sequences and the ability to upload feature tables to Submission Portal for messenger RNA sequences. We provide an overview of the web, application programming and command-line interfaces that allow users to access GenBank data. We also discuss the importance of creating BioProject and BioSample records during submissions, particularly for viruses and metagenomes. Finally, we summarize educational materials and recent community outreach efforts., (Published by Oxford University Press on behalf of Nucleic Acids Research 2024.)

The National Center for Biotechnology Information (NCBI) provides online information resources for biology, including the GenBank® nucleic acid sequence repository and the PubMed® repository of citations and abstracts published in life science journals. NCBI provides search and retrieval operations for most of these data from 31 distinct repositories and knowledgebases. The E-utilities serve as the programming interface for most of these. Resources receiving significant updates in the past year include PubMed, PubMed Central, Bookshelf, the NIH Comparative Genomics Resource, BLAST, Sequence Read Archive, Taxonomy, iCn3D, Conserved Domain Database, Pathogen Detection, antimicrobial resistance resources and PubChem. These resources can be accessed through the NCBI home page at https://www.ncbi.nlm.nih.gov., (Published by Oxford University Press on behalf of Nucleic Acids Research 2024.)

The National Center for Biotechnology Information (NCBI) provides online information resources for biology, including the GenBank® nucleic acid sequence database and the PubMed® database of citations and abstracts published in life science journals. NCBI provides search and retrieval operations for most of these data from 35 distinct databases. The E-utilities serve as the programming interface for most of these databases. Resources receiving significant updates in the past year include PubMed, PMC, Bookshelf, SciENcv, the NIH Comparative Genomics Resource (CGR), NCBI Virus, SRA, RefSeq, foreign contamination screening tools, Taxonomy, iCn3D, ClinVar, GTR, MedGen, dbSNP, ALFA, ClinicalTrials.gov, Pathogen Detection, antimicrobial resistance resources, and PubChem. These resources can be accessed through the NCBI home page at https://www.ncbi.nlm.nih.gov., (Published by Oxford University Press on behalf of Nucleic Acids Research 2023.)

GenBank® (https://www.ncbi.nlm.nih.gov/genbank/) is a comprehensive, public database that contains 25 trillion base pairs from over 3.7 billion nucleotide sequences for 557 000 formally described species. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. Recent updates include policies for including spatio-temporal metadata, clarified documentation for GenBank data processing, enhanced foreign contamination screening tools, new processes in the Submission Portal, migration of Entrez Genome and Assembly displays into NCBI Datasets, and the impending retirement of tbl2asn, replaced by table2asn., (Published by Oxford University Press on behalf of Nucleic Acids Research 2023.)

GenBank® (https://www.ncbi.nlm.nih.gov/genbank/) is a comprehensive, public database that contains 19.6 trillion base pairs from over 2.9 billion nucleotide sequences for 504 000 formally described species. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. Recent updates include resources for data from the SARS-CoV-2 virus, NCBI Datasets, BLAST ClusteredNR, the Submission Portal, table2asn, a Foreign Contamination Screening tool and BioSample., (Published by Oxford University Press on behalf of Nucleic Acids Research 2022.)

The National Center for Biotechnology Information (NCBI) provides online information resources for biology, including the GenBank® nucleic acid sequence database and the PubMed® database of citations and abstracts published in life science journals. NCBI provides search and retrieval operations for most of these data from 35 distinct databases. The E-utilities serve as the programming interface for most of these databases. New resources include the Comparative Genome Resource (CGR) and the BLAST ClusteredNR database. Resources receiving significant updates in the past year include PubMed, PMC, Bookshelf, IgBLAST, GDV, RefSeq, NCBI Virus, GenBank type assemblies, iCn3D, ClinVar, GTR, dbGaP, ALFA, ClinicalTrials.gov, Pathogen Detection, antimicrobial resistance resources, and PubChem. These resources can be accessed through the NCBI home page at https://www.ncbi.nlm.nih.gov., (Published by Oxford University Press on behalf of Nucleic Acids Research 2022.)

The National Center for Biotechnology Information (NCBI) produces a variety of online information resources for biology, including the GenBank® nucleic acid sequence database and the PubMed® database of citations and abstracts published in life science journals. NCBI provides search and retrieval operations for most of these data from 35 distinct databases. The E-utilities serve as the programming interface for the most of these databases. Resources receiving significant updates in the past year include PubMed, PMC, Bookshelf, RefSeq, SRA, Virus, dbSNP, dbVar, ClinicalTrials.gov, MMDB, iCn3D and PubChem. These resources can be accessed through the NCBI home page at https://www.ncbi.nlm.nih.gov., (Published by Oxford University Press on behalf of Nucleic Acids Research 2021.)

GenBank® (https://www.ncbi.nlm.nih.gov/genbank/) is a comprehensive, public database that contains 15.3 trillion base pairs from over 2.5 billion nucleotide sequences for 504 000 formally described species. Recent updates include resources for data from the SARS-CoV-2 virus, including a SARS-CoV-2 landing page, NCBI Datasets, NCBI Virus and the Submission Portal. We also discuss upcoming changes to GI identifiers, a new data management interface for BioProject, and advice for providing contextual metadata in submissions., (Published by Oxford University Press on behalf of Nucleic Acids Research 2021.)

GenBank ® and the Sequence Read Archive (SRA) are comprehensive databases of publicly available DNA sequences. GenBank contains data for 480,000 named organisms, more than 176,000 within the embryophyta, obtained through submissions from individual laboratories and batch submissions from large-scale sequencing projects. SRA contains reads from next-generation sequencing studies from over 110,000 species. Daily data exchange with the European Nucleotide Archive (ENA) in Europe and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage for both databases. GenBank and SRA data are accessible through the NCBI Entrez retrieval system that integrates these data with other data at NCBI, such as genomes, taxonomy, and the biomedical literature. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. Usage scenarios for both GenBank and SRA ranging from local and cloud analyses to online analyses supported by the NCBI web-based tools are discussed. Both GenBank and SRA, along with their related retrieval and analysis services, are available from the NCBI homepage at www.ncbi.nlm.nih.gov ., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

The National Center for Biotechnology Information (NCBI) provides a large suite of online resources for biological information and data, including the GenBank® nucleic acid sequence database and the PubMed® database of citations and abstracts published in life science journals. The Entrez system provides search and retrieval operations for most of these data from 34 distinct databases. The E-utilities serve as the programming interface for the Entrez system. Custom implementations of the BLAST program provide sequence-based searching of many specialized datasets. New resources released in the past year include a new PubMed interface and NCBI datasets. Additional resources that were updated in the past year include PMC, Bookshelf, Genome Data Viewer, SRA, ClinVar, dbSNP, dbVar, Pathogen Detection, BLAST, Primer-BLAST, IgBLAST, iCn3D and PubChem. All of these resources can be accessed through the NCBI home page at https://www.ncbi.nlm.nih.gov., (Published by Oxford University Press on behalf of Nucleic Acids Research 2020.)

GenBank® (https://www.ncbi.nlm.nih.gov/genbank/) is a comprehensive, public database that contains 9.9 trillion base pairs from over 2.1 billion nucleotide sequences for 478 000 formally described species. Daily data exchange with the European Nucleotide Archive and the DNA Data Bank of Japan ensures worldwide coverage. Recent updates include new resources for data from the SARS-CoV-2 virus, updates to the NCBI Submission Portal and associated submission wizards for dengue and SARS-CoV-2 viruses, new taxonomy queries for viruses and prokaryotes, and simplified submission processes for EST and GSS sequences., (Published by Oxford University Press on behalf of Nucleic Acids Research 2020.)

GenBank® (www.ncbi.nlm.nih.gov/genbank/) is a comprehensive, public database that contains over 6.25 trillion base pairs from over 1.6 billion nucleotide sequences for 450 000 formally described species. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. Recent updates include a new version of Genome Workbench that supports GenBank submissions, new submission wizards for viral genomes, enhancements to BankIt and improved handling of taxonomy for sequences from pathogens., (Published by Oxford University Press on behalf of Nucleic Acids Research 2019.)

The National Center for Biotechnology Information (NCBI) provides a large suite of online resources for biological information and data, including the GenBank® nucleic acid sequence database and the PubMed database of citations and abstracts published in life science journals. The Entrez system provides search and retrieval operations for most of these data from 35 distinct databases. The E-utilities serve as the programming interface for the Entrez system. Custom implementations of the BLAST program provide sequence-based searching of many specialized datasets. New resources released in the past year include a new PubMed interface, a sequence database search and a gene orthologs page. Additional resources that were updated in the past year include PMC, Bookshelf, My Bibliography, Assembly, RefSeq, viral genomes, the prokaryotic genome annotation pipeline, Genome Workbench, dbSNP, BLAST, Primer-BLAST, IgBLAST and PubChem. All of these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov., (Published by Oxford University Press on behalf of Nucleic Acids Research 2019.)

GenBank® (www.ncbi.nlm.nih.gov/genbank/) is a comprehensive database that contains publicly available nucleotide sequences for 420 000 formally described species. Most GenBank submissions are made using BankIt, the NCBI Submission Portal, or the tool tbl2asn, and are obtained from individual laboratories and batch submissions from large-scale sequencing projects, including whole genome shotgun (WGS) and environmental sampling projects. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the NCBI Nucleotide database, which links to related information such as taxonomy, genomes, protein sequences and structures, and biomedical journal literature in PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. Recent updates include an expansion of sequence identifier formats to accommodate expected database growth, submission wizards for ribosomal RNA, and the transfer of Expressed Sequence Tag (EST) and Genome Survey Sequence (GSS) data into the Nucleotide database.

The National Center for Biotechnology Information (NCBI) provides a large suite of online resources for biological information and data, including the GenBank® nucleic acid sequence database and the PubMed database of citations and abstracts published in life science journals. The Entrez system provides search and retrieval operations for most of these data from 38 distinct databases. The E-utilities serve as the programming interface for the Entrez system. Augmenting many of the web applications are custom implementations of the BLAST program optimized to search specialized data sets. New resources released in the past year include PubMed Labs and a new sequence database search. Resources that were updated in the past year include PubMed, PMC, Bookshelf, genome data viewer, Assembly, prokaryotic genomes, Genome, BioProject, dbSNP, dbVar, BLAST databases, igBLAST, iCn3D and PubChem. All of these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov.

GenBank® (www.ncbi.nlm.nih.gov/genbank/) is a comprehensive database that contains publicly available nucleotide sequences for 400 000 formally described species. These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole genome shotgun and environmental sampling projects. Most submissions are made using BankIt, the National Center for Biotechnology Information (NCBI) Submission Portal, or the tool tbl2asn. GenBank staff assign accession numbers upon data receipt. Daily data exchange with the European Nucleotide Archive and the DNA Data Bank of Japan ensures worldwide coverage. GenBank is accessible through the NCBI Nucleotide database, which links to related information such as taxonomy, genomes, protein sequences and structures, and biomedical journal literature in PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. Recent updates include changes to sequence identifiers, submission wizards for 16S and Influenza sequences, and an Identical Protein Groups resource., (Published by Oxford University Press on behalf of Nucleic Acids Research 2017.)

GenBank ® (www.ncbi.nlm.nih.gov/genbank/) is a comprehensive database that contains publicly available nucleotide sequences for 370 000 formally described species. These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole genome shotgun (WGS) and environmental sampling projects. Most submissions are made using the web-based BankIt or the NCBI Submission Portal. GenBank staff assign accession numbers upon data receipt. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the NCBI Nucleotide database, which links to related information such as taxonomy, genomes, protein sequences and structures, and biomedical journal literature in PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. Recent updates include changes to policies regarding sequence identifiers, an improved 16S submission wizard, targeted loci studies, the ability to submit methylation and BioNano mapping files, and a database of anti-microbial resistance genes., (Published by Oxford University Press on behalf of Nucleic Acids Research 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

GenBank(®) (www.ncbi.nlm.nih.gov/genbank/) is a comprehensive database that contains publicly available nucleotide sequences for over 340 000 formally described species. Recent developments include a new starting page for submitters, a shift toward using accession.version identifiers rather than GI numbers, a wizard for submitting 16S rRNA sequences, and an Identical Protein Report to address growing issues of data redundancy. GenBank organizes the sequence data received from individual laboratories and large-scale sequencing projects into 18 divisions, and GenBank staff assign unique accession.version identifiers upon data receipt. Most submitters use the web-based BankIt or standalone Sequin programs. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the nuccore, nucest, and nucgss databases of the Entrez retrieval system, which integrates these records with a variety of other data including taxonomy nodes, genomes, protein structures, and biomedical journal literature in PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP., (Published by Oxford University Press on behalf of Nucleic Acids Research 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

GenBank(®) is a comprehensive database of publicly available DNA sequences for 300,000 named organisms, more than 110,000 within the embryophyta, obtained through submissions from individual laboratories and batch submissions from large-scale sequencing projects. Daily data exchange with the European Nucleotide Archive (ENA) in Europe and the DNA Data Bank of Japan ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system that integrates data from the major DNA and protein sequence databases with taxonomy, genome, mapping, protein structure and domain information, as well as the biomedical journal literature in PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. GenBank usage scenarios ranging from local analyses of the data available via FTP to online analyses supported by the NCBI web-based tools are discussed. To access GenBank and its related retrieval and analysis services, go to the NCBI home page at www.ncbi.nlm.nih.gov .

GenBank(®) (http://www.ncbi.nlm.nih.gov/genbank/) is a comprehensive database that contains publicly available nucleotide sequences for over 300 000 formally described species. These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole-genome shotgun and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and GenBank staff assign accession numbers upon data receipt. Daily data exchange with the European Nucleotide Archive and the DNA Data Bank of Japan ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system, which integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP., (Published by Oxford University Press on behalf of Nucleic Acids Research 2014. This work is written by US Government employees and is in the public domain in the US.)

GenBank is a comprehensive database that contains publicly available nucleotide sequences for over 280,000 formally described species. These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole-genome shotgun and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and GenBank staff assign accession numbers upon data receipt. Daily data exchange with the European Nucleotide Archive and the DNA Data Bank of Japan ensures worldwide coverage. GenBank is accessible through the National Center for Biotechnology Information (NCBI) Entrez retrieval system, which integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. To access GenBank and its related retrieval and analysis services, begin at the NCBI home page: www.ncbi.nlm.nih.gov.

The Basic Local Alignment Search Tool (BLAST) website at the National Center for Biotechnology (NCBI) is an important resource for searching and aligning sequences. A new BLAST report allows faster loading of alignments, adds navigation aids, allows easy downloading of subject sequences and reports and has improved usability. Here, we describe these improvements to the BLAST report, discuss design decisions, describe other improvements to the search page and database documentation and outline plans for future development. The NCBI BLAST URL is http://blast.ncbi.nlm.nih.gov.

GenBank® (http://www.ncbi.nlm.nih.gov) is a comprehensive database that contains publicly available nucleotide sequences for almost 260 000 formally described species. These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole-genome shotgun (WGS) and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and GenBank staff assigns accession numbers upon data receipt. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system, which integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. To access GenBank and its related retrieval and analysis services, begin at the NCBI home page: www.ncbi.nlm.nih.gov.

In addition to maintaining the GenBank® nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides analysis and retrieval resources for the data in GenBank and other biological data made available through the NCBI Website. NCBI resources include Entrez, the Entrez Programming Utilities, MyNCBI, PubMed, PubMed Central (PMC), Gene, the NCBI Taxonomy Browser, BLAST, BLAST Link (BLink), Primer-BLAST, COBALT, Splign, RefSeq, UniGene, HomoloGene, ProtEST, dbMHC, dbSNP, dbVar, Epigenomics, Genome and related tools, the Map Viewer, Model Maker, Evidence Viewer, Trace Archive, Sequence Read Archive, BioProject, BioSample, Retroviral Genotyping Tools, HIV-1/Human Protein Interaction Database, Gene Expression Omnibus (GEO), Probe, Online Mendelian Inheritance in Animals (OMIA), the Molecular Modeling Database (MMDB), the Conserved Domain Database (CDD), the Conserved Domain Architecture Retrieval Tool (CDART), Biosystems, Protein Clusters and the PubChem suite of small molecule databases. Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. All of these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov.

GenBank® is a comprehensive database that contains publicly available nucleotide sequences for more than 250,00 formally described species. These sequences are obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole-genome shotgun (WGS) and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and accession numbers are assigned by GenBank staff upon receipt. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system, which integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. To access GenBank and its related retrieval and analysis services, begin at the NCBI home page: www.ncbi.nlm.nih.gov.

In addition to maintaining the GenBank® nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides analysis and retrieval resources for the data in GenBank and other biological data made available through the NCBI Web site. NCBI resources include Entrez, the Entrez Programming Utilities, MyNCBI, PubMed, PubMed Central (PMC), Entrez Gene, the NCBI Taxonomy Browser, BLAST, BLAST Link (BLink), Primer-BLAST, COBALT, Electronic PCR, OrfFinder, Splign, ProSplign, RefSeq, UniGene, HomoloGene, ProtEST, dbMHC, dbSNP, dbVar, Epigenomics, Cancer Chromosomes, Entrez Genomes and related tools, the Map Viewer, Model Maker, Evidence Viewer, Trace Archive, Sequence Read Archive, Retroviral Genotyping Tools, HIV-1/Human Protein Interaction Database, Gene Expression Omnibus (GEO), Entrez Probe, GENSAT, Online Mendelian Inheritance in Man (OMIM), Online Mendelian Inheritance in Animals (OMIA), the Molecular Modeling Database (MMDB), the Conserved Domain Database (CDD), the Conserved Domain Architecture Retrieval Tool (CDART), IBIS, Biosystems, Peptidome, OMSSA, Protein Clusters and the PubChem suite of small molecule databases. Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. All of these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov.

GenBank® is a comprehensive database that contains publicly available nucleotide sequences for more than 380,000 organisms named at the genus level or lower, obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole genome shotgun (WGS) and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and accession numbers are assigned by GenBank staff upon receipt. Daily data exchange with the European Nucleotide Archive (ENA) and the DNA Data Bank of Japan (DDBJ) ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system that integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. To access GenBank and its related retrieval and analysis services, begin at the NCBI Homepage: www.ncbi.nlm.nih.gov.

The National Center for Biotechnology Information (NCBI) hosts 39 literature and molecular biology databases containing almost half a billion records. As the complexity of these data and associated resources and tools continues to expand, so does the need for educational resources to help investigators, clinicians, information specialists and the general public make use of the wealth of public data available at the NCBI. This review describes the educational resources available at NCBI via the NCBI Education page (www.ncbi.nlm.nih.gov/Education/). These resources include materials designed for new users, such as About NCBI and the NCBI Guide, as well as documentation, Frequently Asked Questions (FAQs) and writings on the NCBI Bookshelf such as the NCBI Help Manual and the NCBI Handbook. NCBI also provides teaching materials such as tutorials, problem sets and educational tools such as the Amino Acid Explorer, PSSM Viewer and Ebot. NCBI also offers training programs including the Discovery Workshops, webinars and tutorials at conferences. To help users keep up-to-date, NCBI produces the online NCBI News and offers RSS feeds and mailing lists, along with a presence on Facebook, Twitter and YouTube.

GenBank is a comprehensive database that contains publicly available nucleotide sequences for more than 300,000 organisms named at the genus level or lower, obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects, including whole genome shotgun (WGS) and environmental sampling projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and accession numbers are assigned by GenBank staff upon receipt. Daily data exchange with the European Molecular Biology Laboratory Nucleotide Sequence Database in Europe and the DNA Data Bank of Japan ensures worldwide coverage. GenBank is accessible through the NCBI Entrez retrieval system, which integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bi-monthly releases and daily updates of the GenBank database are available by FTP. To access GenBank and its related retrieval and analysis services, begin at the NCBI homepage: www.ncbi.nlm.nih.gov.

In addition to maintaining the GenBank nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides analysis and retrieval resources for the data in GenBank and other biological data made available through the NCBI web site. NCBI resources include Entrez, the Entrez Programming Utilities, MyNCBI, PubMed, PubMed Central, Entrez Gene, the NCBI Taxonomy Browser, BLAST, BLAST Link (BLink), Electronic PCR, OrfFinder, Spidey, Splign, Reference Sequence, UniGene, HomoloGene, ProtEST, dbMHC, dbSNP, Cancer Chromosomes, Entrez Genomes and related tools, the Map Viewer, Model Maker, Evidence Viewer, Trace Archive, Sequence Read Archive, Retroviral Genotyping Tools, HIV-1/Human Protein Interaction Database, Gene Expression Omnibus, Entrez Probe, GENSAT, Online Mendelian Inheritance in Man, Online Mendelian Inheritance in Animals, the Molecular Modeling Database, the Conserved Domain Database, the Conserved Domain Architecture Retrieval Tool, Biosystems, Peptidome, Protein Clusters and the PubChem suite of small molecule databases. Augmenting many of the web applications are custom implementations of the BLAST program optimized to search specialized data sets. All these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov.

GenBank is a comprehensive database that contains publicly available nucleotide sequences for more than 300,000 organisms named at the genus level or lower, obtained primarily through submissions from individual laboratories and batch submissions from large-scale sequencing projects. Most submissions are made using the web-based BankIt or standalone Sequin programs, and accession numbers are assigned by GenBank(R) staff upon receipt. Daily data exchange with the European Molecular Biology Laboratory Nucleotide Sequence Database in Europe and the DNA Data Bank of Japan ensures worldwide coverage. GenBank is accessible through the National Center for Biotechnology Information (NCBI) Entrez retrieval system, which integrates data from the major DNA and protein sequence databases along with taxonomy, genome, mapping, protein structure and domain information, and the biomedical journal literature via PubMed. BLAST provides sequence similarity searches of GenBank and other sequence databases. Complete bimonthly releases and daily updates of the GenBank database are available by FTP. To access GenBank and its related retrieval and analysis services, begin at the NCBI Homepage: www.ncbi.nlm.nih.gov.

In addition to maintaining the GenBank nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides analysis and retrieval resources for the data in GenBank and other biological data made available through the NCBI web site. NCBI resources include Entrez, the Entrez Programming Utilities, MyNCBI, PubMed, PubMed Central, Entrez Gene, the NCBI Taxonomy Browser, BLAST, BLAST Link (BLink), Electronic PCR, OrfFinder, Spidey, Splign, RefSeq, UniGene, HomoloGene, ProtEST, dbMHC, dbSNP, Cancer Chromosomes, Entrez Genomes and related tools, the Map Viewer, Model Maker, Evidence Viewer, Clusters of Orthologous Groups (COGs), Retroviral Genotyping Tools, HIV-1/Human Protein Interaction Database, Gene Expression Omnibus (GEO), Entrez Probe, GENSAT, Online Mendelian Inheritance in Man (OMIM), Online Mendelian Inheritance in Animals (OMIA), the Molecular Modeling Database (MMDB), the Conserved Domain Database (CDD), the Conserved Domain Architecture Retrieval Tool (CDART) and the PubChem suite of small molecule databases. Augmenting many of the web applications is custom implementation of the BLAST program optimized to search specialized data sets. All of the resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov.

A model of the carbohydrate recognition domain of the serum form of mannose-binding protein (MBP) from rat complexed with methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside is presented. Allowed conformations for the bound sugar were derived from simulated annealing protocols incorporating distance restraints computed from transferred NOESY spectra. The resulting sugar conformations were then modeled into the MBP binding site, and these models of the complex were refined using molecular dynamics (MD) simulations in the presence of solvent water. These studies indicate that only one of the two major conformations of the alpha(1-->6) linkage found in solution is significantly populated in the bound state (omega = 60 degrees ), whereas the alpha(1-->3) linkage samples at least two states, similar to its behavior in free solution. The bound conformation allows direct hydrogen bonds to form between the sugar and K182 of MBP, in addition to other water-mediated hydrogen bonds. Estimates of binding constants of candidate complexes based on changes in solvent-accessible surface areas upon binding support the NMR and MD results. These estimates further suggest that the enthalpic gains of the additional sugar-MBP interactions in a trisaccharide as opposed to a monosaccharide are offset by entropic penalties, offering an explanation for previous binding data.

We illustrate an approach that uses the backbone carbonyl chemical shift to relieve resonance overlaps in triple-resonance assignment experiments conducted on protein samples. We apply this approach to two cases of simultaneous overlaps: those of ((1)H(N), (15)N) spin pairs and those of ((1)H(alpha), (13)C(alpha)) spin pairs in residues preceding prolines. For these cases we employed respectively CBCACO(N)H and H(CA)CON experiments, simple variants of the commonly used CBCA(CO)NH and HCA(CO)N experiments obtained by replacing one of the indirect dimensions with a carbonyl dimension. We present data collected on ribosomal protein S4 using these experiments, along with overlap statistics for four other polypeptides ranging in size from 76 to 263 residues. These data indicate that the CBCACO(N)H, in combination with the CBCA(CO)NH, can relieve >83% of the ((1)H(N), (15)N) and ((1)H(N), (13)C') overlaps for these proteins. The data also reveal how the H(CA)CON experiment successfully completed the assignment of triply and quadruply degenerate X-Pro spin systems in a mobile, proline-rich region of S4, even when X was a glycine. Finally, we discuss the relative sensitivities of these experiments compared to those of existing sequences, an analysis that reinforces the usefulness of these experiments in assigning extensively overlapped and/or proline-rich sequences in proteins.

N-linked oligosaccharides often act as ligands for receptor proteins in a variety of cell recognition processes. Knowledge of the solution conformations, as well as protein-bound conformations, of these oligosaccharides is required to understand these important interactions. In this paper we present a model for the solution conformations sampled by a simple trimannoside, methyl 3, 6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside, which contains two of the most commonly found glycosidic linkages in N-linked oligosaccharides. This model was derived from simulated annealing protocols incorporating distance restraints extracted from NOESY spectra along with torsional restraints computed from three-bond (1)H-(13)C coupling constants measured across the glycosidic bonds. The model was refined in light of unrestrained molecular dynamics simulations conducted in the presence of solvent water. The resulting model depicts a molecule undergoing conformational averaging in solution, adopting four major and two minor conformations. The four major conformations arise from a pair of two-state transitions, one each at the alpha(1-->3) and alpha(1-->6) linkages, whereas the minor conformations result from an additional transition of the alpha(1-->6) linkage. Our data also suggest that the alpha(1-->3) transition is fast and changes the molecular shape slightly, whereas the alpha(1-->6) is much slower and alters the molecular shape dramatically.

Protein S4, a component of the 30S subunit of the prokaryotic ribosome, is one of the first proteins to interact with rRNA in the process of ribosome assembly and is known to be involved in the regulation of this process. While the structure of the C-terminal 158 residues of Bacillus stearothermophilus S4 has been solved by both X-ray crystallography and NMR, that of the N-terminal 41 residues is unknown. Evidence suggests that the N-terminus is necessary both for the assembly of functional ribosomes and for full binding to 16S RNA, and so we present NMR data collected on the full-length protein (200 aa). Our data indicate that the addition of the N-terminal residues does not significantly change the structure of the C-terminal 158 residues. The data further indicate that the N-terminus is highly flexible in solution, without discernible secondary structure. Nevertheless, structure calculations based on nuclear Overhauser effect spectroscopic data combined with (15)N relaxation data revealed that two short segments in the N-terminus, S(12)RRL(15) and P(30)YPP(33), adopt transiently ordered states in solution. The major conformation of S(12)RRL(15) appears to orient the arginine side chains outward toward the solvent in a parallel fashion, while that of P(30)YPP(33) forms a nascent turn of a polyproline II helix. These segments contain residues that are highly conserved across many prokaryotic species, and thus they are reasonable candidates respectively for sites of interaction with RNA and other ribosomal proteins within the intact ribosome.

We present heteronuclear two-dimensional methods for the analysis of the geometry of exchangeable protons on a protein-bound carbohydrate. By using a water-selective NOESY-HSQC, we observed cross-relaxation between carbohydrate hydroxyl protons and non-exchangeable ring protons in the complex of [13C6]-alpha-methyl-D-mannopyranoside with recombinant rat mannose binding protein. Using a simple kinetic model, we were able to explain the differences in the initial slopes of the resulting cross-relaxation buildup curves in terms of the geometry of the hydroxyl protons in the bound state. The hydroxyl rotamers consistent with our cross-relaxation data fit very well with predictions based on the crystal structure of MBP bound to a mannose-rich oligosaccharide. These methods should be applicable to other systems where both ligand exchange and water exchange are fast relative to the rate of cross-relaxation.

In order to investigate the possible importance of Hoogsteen base pairing to the DNA-binding ability of echinomycin, quantitative DNase I footprinting has been performed. The substrate was the tyrT DNA restriction fragment, either "native" or substituted with one of the purine analogs 2'-deoxy-7-deazaadenosine and 2'-deoxy-7-deazaguanosine in both strands. The modified DNA species were prepared by PCR and selectively labeled at the 5' terminus of one strand (usually the upper "Watson" strand) with [32P]ATP and polynucleotide kinase. Proper incorporation of the analog nucleotides was verified by Maxam-Gilbert G- and C-sequencing reactions as well as exposure to osmium tetroxide and diethyl pyrocarbonate. OsO4 was found to react strongly with the 7-deaza nucleotides, providing a good check of faithful incorporation. The previously observed echinomycin-induced hyperreactivity of purines toward diethyl pyrocarbonate was eliminated by incorporating the appropriate 7-deazapurine. The DNase I footprinting titration studies greatly refined the existing knowledge of the DNA-binding characteristics of echinomycin, as they revealed five general types of concentration-dependent behavior at single-bond resolution. Estimates of microscopic binding constants at individual DNA binding sites were obtained by measuring the antibiotic concentration which produced a half-maximal effect on the concentration of a given DNase I cleavage product. All binding sites contained one or more CpG steps, and all CpG steps analyzed formed part of a binding site for echinomycin. No consistent differences in the estimated binding constants for these sites were observed by comparing normal and modified DNAs, indicating that the abolition of formal Hoogsteen pairs did not significantly alter the thermodynamics of echinomycin-DNA interaction. The lack of any detectable decrease in binding constants for critical sites in the 7-deazapurine-substituted DNAs argues against any anti-syn conformational transition of purine nucleosides occurring in association with the bis-intercalative complex formation.