TAXON-SPECIFIC PROTEIN OF THE FROG LENS - PHYLOGENETIC RELATEDNESS WITH THE PROTEINS OF NADP-DEPENDED REDUCTASES SUPERFAMILY

Physico-chemical and molecular-biological properties of the proteins f rom the family of NADP-dependent reductases are reviwed in the article . Physico-chemical properties of aldehyde/aldosoreductases are well st udied. Information on the genes, coding for these proteins has appeare d recently as well. Comparison of the protein structures has revealed, that taxon-specific protein of the frog lens-rho-crystallin - is stru cturally related to the superfamily of NADP-dependent reductases, thou gh 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 memb ers of superfamily, including rho-crystallin. All the data presented e nable to suppose, that rho-crystallin and other members of superfamily have a common ancestor gene. A set of successive duplications and mut ations of the ancestor gene resulted in the appearance of rho-crystall in gene, that has lost the enzymatic activity and acquired the ability for tissue specific superexpression in the lens cells.