RHO-B-CRYSTALLIN, AN ALDOSE REDUCTASE-LIKE LENS PROTEIN IN THE GECKO LEPIDODACTYLUS-LUGUBRIS

The ocular lenses of the diurno-nocturnal gecko Lepidodactylus lugubri s contain a monomeric 38-kDa protein at a level of 20 to 22% of the to tal water-soluble protein. Amino acid sequences of peptides from this protein are most similar - up to 72% identity - to mammalian aldose re ductase, an NADPH-dependent reductase which normally occurs at house-k eeping levels in the eye lens, and which is involved in the developmen t of diabetic cataract. The sequences show 56% identity with rho-cryst allin from lenses of the frog genus Rana. It is concluded that differe nt genes from the same superfamily of NADPH-dependent reductases have been recruited to become highly expressed as lens proteins in at least two different evolutionary lineages. To reflect the relationship with fog rho-crystallin, the gecko lens protein is designated as rho B-cry stallin. As for frog rho-crystallin, no enzymatic activity could be es tablished for rho B-crystallin in the gecko, lens. Up to now, rho B-cr ystallin has not been detected in lenses of other reptiles or amphibia ns. (C) 1995 Academic Press, Inc.