Increased calcium binding capacity associated with genotypic lens opacities

HY-1 genotype chick lenses display epithelial hyperplasia and associated lens opacities. Membrane proteins from HY-1 and normal chick lenses were separated by isoelectric focusing, and 45Ca2+ binding capacities were determined. Markedly higher (congruent to 900-fold) binding of 45Ca2+ was observed in high molecular weight membrane proteins of HY-1 chick lenses compared with similar fractions from normal lenses. It is suggested that the increased calcium binding capacity may be due to ionic imbalances caused by elevated sialic acid in HY-1 cataractous lenses.