Classification of Rat Lens Crystallins and Identification of Proteins Encoded by Rat Lens mRNA

Abstract

Endogenous rat lens crystallins were separated by gel filtration into 4 fractions, .alpha., .beta.H, .beta.L and .gamma.-crystallin. Elution patterns of soluble lens proteins from animals of different ages show a relative decrease of .beta.H and .gamma.-crystallin during aging. Conversely the relative amounts of .alpha. and .beta.L-crystallin are enhanced. The rat crystallin subunits from the 4 fractions were characterized by 1-dimensional and 2-dimensional gel electrophoretic techniques. From the results a classification could be derived and a nomenclature for the soluble rat lens proteins is proposed. The products synthesized by rat lens mRNA in a heterologous cell-free system were also characterized. Co-electrophoresis of the radioactive products synthesized de novo together with the isolated unlabeled protein fractions on 2-dimensional gels shows the relation between primary gene products and their posttranslationally modified derivatives.