title: Human interstitial retinoid-binding protein. Gene structure and primary structure.
abstract: Interstitial retinoid-binding protein (IRBP) is synthesized and secreted by rod photoreceptor cells into the interphotoreceptor matrix and is known to bind retinoids and fatty acids. We have used cDNA clones encoding human IRBP to isolate a 15-kilobase genomic fragment that encompasses the complete human IRBP gene. The IRBP gene spans more than 11 kilobases and is interrupted by three introns, all of which are positioned near the 3'-end of the coding sequence. The 3741-base pair coding region of IRBP appears to have been generated by quadruplication of an approximately 900 base pair long ancestral gene. The deduced amino acid sequence predicts a mature protein of 1,230 residues (calculated molecular weight 133,000). The protein sequence can be aligned into four homologous segments, each consisting of about 300 residues. Sequence similarity between segments is as high as 60% when conservative substitutions are taken into account. Two putative N-linked glycosylation sites are located in highly conserved domains in the center of the first and second segment of IRBP. A domain consisting of 41 residues at the COOH-terminal end of the third segment has 15 matching residues (38%) with an intradiscal loop of rhodopsin, a retinal-binding protein in rod photoreceptors.
authors.affiliation: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas 77030.
authors.forename: G I
authors.initials: GI
authors.lastname: Liou
authors.forename: D P
authors.initials: DP
authors.lastname: Ma
authors.forename: Y W
authors.initials: YW
authors.lastname: Yang
authors.forename: L
authors.initials: L
authors.lastname: Geng
authors.forename: C
authors.initials: C
authors.lastname: Zhu
authors.forename: W
authors.initials: W
authors.lastname: Baehr
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003062:Codon; D015342:DNA Probes; D004262:DNA Restriction Enzymes; D004720:Endonucleases; D005091:Exons; D005136:Eye Proteins; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D012160:Retina / Q000032:analysis; D012177:Retinol-Binding Proteins / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D015719:Single-Strand Specific DNA and RNA Endonucleases; D014158:Transcription, Genetic; D000099214:Retinol-Binding Proteins, Interstitial
chemical_list: D003062:Codon; D015342:DNA Probes; D004262:DNA Restriction Enzymes; D004720:Endonucleases; D005136:Eye Proteins; D012333:RNA, Messenger; D012177:Retinol-Binding Proteins; D015719:Single-Strand Specific DNA and RNA Endonucleases; D000099214:Retinol-Binding Proteins, Interstitial