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Cloning, expression and functional characterization of the putative regeneration and tolerance factor (RTF/TJ6) as a functional vacuolar ATPase proton pump regulatory subunit with a conserved sequence of immunoreceptor tyrosine-based activation motif.
- Source :
-
International immunology [Int Immunol] 2005 Oct; Vol. 17 (10), pp. 1303-13. Date of Electronic Publication: 2005 Aug 19. - Publication Year :
- 2005
-
Abstract
- In an attempt to identify new immunoreceptor tyrosine-based activation motif (ITAM)-containing human molecules that may regulate hitherto unknown immune cell functions, we BLAST searched the National Center for Biotechnology Information database for ITAM-containing sequences. A human expressed sequence tag showing partial homology to the murine TJ6 (mTJ6) gene and encoding a putative ITAM sequence has been identified and used to clone the human TJ6 (hTJ6) gene from an HL-60-derived cDNA library. hTJ6 was found to encode a protein of 856 residues with a calculated mass of 98 155 Da. Immunolocalization and sequence analysis revealed that hTJ6 is a membrane protein with predicted six transmembrane-spanning regions, typical of ion channels, and a single putative ITAM (residues 452-466) in a juxtamembrane or hydrophobic intramembrane region. hTJ6 is highly homologous to Bos taurus 116-kDa subunit of the vacuolar proton-translocating ATPase. Over-expression of hTJ6 in HEK 293 cells increased H+ uptake into intracellular organelles, an effect that was sensitive to inhibition by bafilomycin, a selective inhibitor of vacuolar H+ pump. Northern blot analysis demonstrated three different hybridizing mRNA transcripts corresponding to 3.2, 5.0 and 7.3 kb, indicating the presence of several splice variants. Significant differences in hTJ6 mRNA levels in human tissues of different origins point to possible tissue-specific function. Although hTJ6 was found to be a poor substrate for tyrosine-phosphorylating enzymes, suggesting that its ITAM sequence is non-functional in protein tyrosine kinase-mediated signaling pathways, its role in organellar H+ pumping suggests that hTJ6 function may participate in protein trafficking/processing.
- Subjects :
- Amino Acid Motifs immunology
Amino Acid Sequence
Animals
Blotting, Northern
Cattle
Cell Line
Cloning, Molecular
Conserved Sequence
Humans
Jurkat Cells
Molecular Sequence Data
Pregnancy Proteins biosynthesis
Pregnancy Proteins physiology
Protein Processing, Post-Translational immunology
Protein Subunits physiology
Protein Transport immunology
Receptors, Immunologic genetics
Sequence Alignment
Sequence Homology, Amino Acid
Suppressor Factors, Immunologic biosynthesis
Suppressor Factors, Immunologic physiology
Tyrosine genetics
Tyrosine metabolism
Vacuolar Proton-Translocating ATPases biosynthesis
Vacuolar Proton-Translocating ATPases genetics
Pregnancy Proteins chemistry
Pregnancy Proteins genetics
Protein Subunits chemistry
Protein Subunits genetics
Suppressor Factors, Immunologic chemistry
Suppressor Factors, Immunologic genetics
Tyrosine chemistry
Vacuolar Proton-Translocating ATPases physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0953-8178
- Volume :
- 17
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- International immunology
- Publication Type :
- Academic Journal
- Accession number :
- 16113235
- Full Text :
- https://doi.org/10.1093/intimm/dxh308