GENOMICS 36, 424 –430 (1996) ARTICLE NO. 0487 Primary Structure of Human 11-cis Retinol Dehydrogenase and Organization and Chromosomal Localization of the Corresponding Gene ANDRA ` S S IM ON,* J ACOB L AGERCRANTZ,² S VETLANA B AJALICA-L AGERCRANTZ,² AND ULF E RIKSSON* ,1 * Ludwig Institute for Cancer Research, Stockholm Branch, Box 240, S-171 77 Stockholm, Sweden; and ² Clinical Genetics Unit, Department of Molecular Medicine, Karolinska Hospital, S-171 76 Stockholm, Sweden Received December 13, 1995; accepted July 4, 1996 ceptor cells to all-trans retinol (Bliss, 1948; Wald and The universal chromophore of visual pigments in Hubbard, 1949). higher animals is 11-cis retinaldehyde. The final step 11-cis Retinaldehyde is generated in the retinal pig- in the biosynthetic pathway generating this compound ment epithelium (RPE) 2 (Das and Gouras, 1988). All- is catalyzed by 11-cis retinol dehydrogenase, a mem- trans retinol, the ultimate precursor in this process, is brane-bound enzyme abundantly expressed in the reti- accumulated by the RPE from the photoreceptor cells nal pigment epithelium of the eye. In this work we following light exposure of the visual pigments and demonstrate that the primary structure of human 11- from plasma retinol-binding protein present in the gen- cis retinol dehydrogenase is highly conserved with eral circulation. Following the isomerization of all- 91% identity to the bovine enzyme. The gene encoding trans retinol into 11-cis retinol via an all-trans reti- 11-cis retinol dehydrogenase spans over É4.1 kb of nylester intermediate (Bernstein and Rando, 1986; DNA and is divided into four translated exons. Analy- Bridges and Alvarez, 1988), 11-cis retinol is oxidized sis of a panel of somatic cells hybrids and fluorescence into 11-cis retinaldehyde. This last metabolic step is in situ hybridization on metaphase chromosomes re- catalyzed by the stereo-specific enzyme 11-cis retinol vealed that the gene is located on chromosome 12q13– dehydrogenase (11-cis RDH) (Lion et al., 1975), in a q14. Due to the unique role of 11-cis retinol dehydroge- reaction requiring NAD / as the cofactor. The 11-cis nase in the generation of visual pigments, it is a candi- RDH is a 32-kDa membrane-bound enzyme abundantly date gene for involvement in hereditary eye disease. expressed by the RPE (Simon et al., 1995). This enzyme  1996 Academic Press, Inc. is the first identified retinol-metabolizing enzyme be- longing to the family of short-chain alcohol dehydroge- nases/reductases (SDR), a large family of enzymes that INTRODUCTION metabolize a variety of substrates including steroids, prostaglandins, and fatty acids (Jo ¨ rnvall et al., 1995). Vitamin A derivatives play a central role in the biol- Recently, three additional retinol dehydrogenases ogy of the eye and particularly in the visual processes closely related to 11-cis RDH have been identified (Chai (for a recent review see Saari, 1994). The universal et al., 1995a,b, 1996). chromophore of all visual pigments in higher animals It is well known that inability to synthesize func- is 11-cis retinaldehyde, a metabolite of all-trans retinol tional visual pigments is a common cause of hereditary (vitamin A alcohol). In the photoreceptor cells of the retinal degeneration, a group of diseases collectively eye, 11-cis retinaldehyde is covalently complexed to the known as retinitis pigmentosa (for a review see Berson, opsins, the protein moieties of the visual pigments. 1993). The most common forms of autosomal dominant Upon light exposure, 11-cis retinaldehyde undergoes retinitis pigmentosa affect rhodopsin, the protein moi- an 11-cis to all-trans isomerization, and this change in ety of the rod visual pigments. Much less is known molecular structure of the visual pigments initiates a with regard to the role of 11-cis retinaldehyde in the series of events in the photoreceptor cells that eventu- biogenesis of functional visual pigments and the possi- ally lead to visual perception (Wald, 1968). All-trans bility that failure to synthesize this compound may be retinaldehyde is subsequently reduced in the photore- involved in hereditary retinal degeneration. The nucleotide sequence of the cDNA encoding human 11-cis reti- nol dehydrogenase has been deposited with the GenBank/EBI Data 2 Abbreviations used: RPE, retinal pigment epithelium; bp, base- pair(s); DAPI, 4,6-diamino-2-phenyl-indole; HSD, hydroxysteroid de- Bank under the Accession No. U43559. 1 To whom correspondence should be addressed. Telephone: /46-8-728 hydrogenase; nt, nucleotide(s); 11-cis RDH, 11-cis retinol dehydroge- nase; SDR(s), short-chain alcohol dehydrogenase(s)/reductase(s). 7109. Fax: /46-8-332812. E-mail: Ulf _Eriksson@ludwigmac1.lw.ki.se. 424 0888-7543/96 $18.00 Copyright  1996 by Academic Press, Inc. All rights of reproduction in any form reserved.