[The taxon-specific lens protein of the frog eye: its phylogenetic kinship with the proteins of the NADP-dependent reductase family].

: Physicochemical and molecular-biological properties of the proteins from the family of NADP-dependent reductases are reviewed in the article. Physicochemical properties of aldehyde/aldosoreductases are well studied. Information on the genes, coding for these proteins has appeared recently as well. Comparison of the protein structures has revealed, that taxon-specific protein of the frog lens-rho-crystallin--is structurally related to the superfamily of NADP-dependent reductases, though it does not have an enzymatic activity. Sequence alignment reveals a set of clusters, conserved in all members of superfamily. Among them there are two highly conserved regions, providing for binding of NADP coenzyme. Secondary structure of the proteins is similar as well. All the members of superfamily predominantly have beta-sheets. Comparison of structural data for proteins, isolated from various organisms from bacterium to human, suggests phylogenetic relatedness of all the members of superfamily, including rho-crystallin. All the data presented enable to suppose, that rho-crystallin and other members of superfamily have a common ancestor gene. A set of successive duplications and mutations of the ancestor gene resulted in the appearance of rho-crystallin gene, that has lost the enzymatic activity and acquired the ability for tissue specific superexpression in the lens cells.