A retinaldehyde dehydrogenase as a structural protein in a mammalian eye lens. Gene recruitment of eta-crystallin.
eta-Crystallin is a taxon-specific crystallin, a major component of the eye lens in elephant shrews (Macroscelidea). Sequence analysis of eta-crystallin from two genera of elephant shrews and expression of recombinant eta-crystallin show that the protein is a cytoplasmic (class 1) aldehyde dehydrogenase (ALDH1, EC 1.2.1.3) with activity for the oxidation of retinaldehyde to retinoic acid. Unlike many other mammals, elephant shrews have two ALDH1 genes. One encodes ALDH1/eta-crystallin which, in addition to its very high expression in lens, is also the predominant form of ALDH1 expressed in other parts of the eye. The second gene encodes a "non-lens" ALDH1 (ALDH1-nl) which is the predominant form expressed in liver. This pattern of tissue preference contrasts with other mammals which make use of the same major ALDH1 transcript in both ocular and non-ocular tissues. Thus the gene recruitment of ALDH1/eta-crystallin as a structural protein in elephant shrew lenses is associated with its collateral recruitment as the major form of ALDH1 expressed in other parts of the eye.
Graham
C
C
Section on Molecular Structure and Function, Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2730, USA.
Hodin
J
J
Wistow
G
G
D000445:Aldehyde Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003459:Crystallins / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005796:Genes; D006801:Humans; D007908:Lens, Crystalline / Q000201:enzymology* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D010802:Phylogeny; D011994:Recombinant Proteins; D050697:Retinal Dehydrogenase; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012788:Shrews / Q000235:genetics*; D014018:Tissue Distribution
D003459:Crystallins; D018076:DNA, Complementary; D011994:Recombinant Proteins; D000445:Aldehyde Oxidoreductases; D050697:Retinal Dehydrogenase