The retinal pigment epithelial-specific 11-cis retinol dehydrogenase belongs to the family of short chain alcohol dehydrogenases.
We have isolated and partially characterized a 32-kDa membrane-associated protein (p32), which forms a complex with p63, an abundant membrane protein in bovine retinal pigment epithelium. The sequence of a cDNA clone for p32 revealed an open reading frame encoding 318 amino acid residues. Several hydrophobic regions could be identified, suggesting that p32 is an integral membrane protein. A search of data bases identified p32 as a member of the superfamily of short chain alcohol dehydrogenases. Transcripts for p32 were specifically expressed in retinal pigment epithelium. Overexpression of p32 in Cos cells produced a membrane-bound stereospecific 11-cis retinol dehydrogenase, active in the presence of NAD+ as cofactor but not in the presence of NADP. We propose that p32 is the stereospecific 11-cis retinol dehydrogenase, which catalyzes the final step in the biosynthesis of 11-cis retinaldehyde, the universal chromophore of visual pigments.
Ludwig Institute for Cancer Research, Stockholm Branch, Sweden.
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A
Simon
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U
Hellman
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Wernstedt
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Eriksson
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D008969:Molecular Sequence Data; D010857:Pigment Epithelium of Eye / Q000201:enzymology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D011994:Recombinant Proteins; D000429:Alcohol Oxidoreductases; C022520:retinol dehydrogenase