Molecular biology: recent studies on enzyme/crystallins and alpha-crystallin gene expression

Abstract

Jin H. Kinoshita has had a major role in fostering investigations on the molecular biology of the eye during his tenure as Scientific Director of the National Eye Institute (N.E.I.). His appreciation and support of molecular biology have been the basis for many advances in this area in the N.E.I. and have led to a fertile breeding ground for molecular studies on the normal and diseased eye. Our recent studies have shown that the taxon-specific crystallins have been recruited from numerous metabolic enzymes; they are expressed in the lens as abundant structural proteins and in other tissues as enzymes, a situation we call gene sharing. Although not taxon-specific, alpha B-crystallin, structurally related to the small heat-shock proteins, is expressed in diverse tissues; by contrast, alpha A-crystallin appears to be lens-specific. Recombinant DNA studies indicate that the two alpha-crystallin genes use different promoter sequences and trans factors for their expression. Thus, the ubiquitous alpha-crystallin genes may provide some insight into the mechanisms used to recruit metabolic enzymes as taxon-specific lens crystallins.