COMPARATIVE-ANALYSIS OF THE ZETA-CRYSTALLIN QUINONE REDUCTASE GENE INGUINEA-PIG AND MOUSE

zeta-Crystallin is a novel nicotinamide adenine dinucleotide phosphate :quinone reductase, present at enzymatic levels in various tissues of different species, which is highly expressed in the lens of some hystr icomorph rodents and camelids. We report here the complementary DNA (c DNA) cloning of zeta-crystallin from liver libraries in guinea pig (Ca via porcellus), where zeta-crystallin is highly expressed in the lens, and in the laboratory mouse (Mus musculus), where expression in the l ens occurs only at enzymatic levels. A 5' untranslated sequence differ ent from the one previously reported for the guinea pig lens cDNA was found in these clones. We also report the isolation of genomic clones including the complete guinea pig zeta-crystallin gene and the 5' regi on of this gene in mouse. These results show the presence of two promo ters in the guinea pig zeta-crystallin gene, one responsible for expre ssion at enzymatic levels and the other responsible for the high expre ssion in the lens. The guinea pig lens promoter is not present in the mouse gene. This is the first example in which the recruitment of an e nzyme as a lens crystallin can be explained by the acquisition of an a lternative lens-specific promoter.