Search

The universal chromophore of visual pigments in higher animals is 11-cis retinaldehyde. The final step in the biosynthetic pathway generating this compound is catalyzed by 11-cis retinol dehydrogenase, a membrane-bound enzyme abundantly expressed in the retinal pigment epithelium of the eye. In this work we demonstrate that the primary structure of human 11-cis retinol dehydrogenase is highly conserved with 91% identity to the bovine enzyme. The gene encoding 11-cis retinol dehydrogenase spans over approximately 4.1 kb of DNA and is divided into four translated exons. Analysis of a panel of somatic cells hybrids and fluorescence in situ hybridization on metaphase chromosomes revealed that the gene is located on chromosome 12q13-q14. Due to the unique role of 11-cis retinol dehydrogenase in the generation of visual pigments, it is a candidate gene for involvement in hereditary eye disease.

Glutaredoxin is a small protein (12 kDa) catalyzing glutathione-dependent disulfide oxidoreduction reactions in a coupled system with NADPH, GSH, and glutathione reductase. A cDNA encoding the human glutaredoxin gene (HGMW-approved symbol GLRX) has recently been isolated and cloned from a human fetal spleen cDNA library. The screening of a human genomic library in Charon 4A led to the identification of three genomic clones. Using fluorescence in situ hybridization to metaphase chromosomes with one genomic clone as a probe, the human glutaredoxin gene was localized to chromosomal region 5q14. This localization at chromosome 5 was in agreement with the somatic cell hybrid analysis, using DNA from a human-hamster and a human-mouse hybrid panel and using a human glutaredoxin cDNA as a probe.

We describe the isolation, characterization, and genomic structure of a gene, Phospholipase C beta 3 Neighboring gene (PNG), located on chromosome 11q13. The cDNA was isolated using a cosmid that also contains the phospholipase C beta 3 gene (PLCB3). PNG does not have any marked similarity to other known genes on the DNA level. However, analysis of hybridization to a panel of somatic cell hybrids indicates the existence of related sequences on chromosomes 2, 4, 7, and 22. PNG showed expression of a 1-kb message in multiple tissues. The predicted protein is 199 amino acids. The gene spans approximately 2.5 kb, divided into four exons and three introns. It is located 4.4 kb upstream of PLCB3, with the 5' ends facing each other. The intergenic region has been completely sequenced, revealing separate CpG islands at both ends of this region. The islands are separated by a stretch of 2 kb, characterized by periodic alteration of the GC content. The 5'-flanking region of PNG does not contain TATA or CCAAT, suggesting a housekeeping promoter structure.

We have characterized the complete cDNA sequence, genomic structure, and expression of the human phosphoinositide-specific phospholipase C beta 3 (PLC beta 3) gene (gene symbol PLCB3). PLC beta 3 plays an important role in initiating receptor-mediated signal transduction. Activation of PLC takes place in many cells as a response to stimulation by hormones, growth factors, neurotransmitters, and other ligands. The partial cDNA sequence of PLC beta 3, previously published, was extended with 876 bp in the 5' direction, giving a transcript of 4400 bp and a total open reading frame of 1234 amino acids. This was in accordance with expression analysis by Northern blotting that revealed a single 4.4-kb transcript in all tissues tested. Genomic data were obtained by sequencing plasmid subclones of a cosmid that contained the whole gene. The size of the complete transcription unit was estimated to be on the order of 15 kb. The gene contains 31 exons, with all splice donor and acceptor sites conforming to the GT/AG rule. No exon exceeds 571 bp in length, and the shortest exon spans only 36 bp. More than half of the introns are smaller than 200 bp, with the smallest being only 79 bp long. The transcription initiation site was determined to be within an 8-bp cluster 328-321 bp upstream of the translation initiation site. The 5'flanking region is highly GC rich, with multiple CpG doublets, and contains multiple binding sites for Sp1. Lacking typical transcriptional regulatory sequences such as TATA and CAAT boxes, the putative promoter region conforms to the group of housekeeping promoters.