The Emory mouse cataract: changes in the beta and gamma-crystallins during aging and cataractogenesis as revealed by isoelectric focusing of the native soluble proteins.

Isoelectric focusing on ultra-thin polyacrylamide gels was employed to study alterations in the distribution patterns of soluble beta and gamma-crystallins during the development of cataract in the Emory (EM) mouse. These alterations were compared with corresponding changes occurring in clear control lenses of the same age from the cataract-resistant (CR) strain. At two months of age both strains gave similar patterns. At four and fourteen months the EM lens showed depressed beta peaks compared to the CR lens. At fourteen months the EM lens had reduced gamma 2 and gamma 5 compared with the CR lens. At twenty-four months the EM lens had all gamma's markedly reduced, especially gamma 5, with the complete disappearance of gamma 4 which was however still present in the CR lens at twenty-six months. At twenty-four months the EM lens had a relatively large amount of beta 5 but no beta 5a or beta 5b; the latter two were present in the CR lens surrounding beta 5 which was less prominent than in the EM lens. The decrease in gamma's in the twenty-four months EM lens was approximately equalled by an apparent increase in beta's. Of the above changes only the decrease in beta's at four months can be considered precataractous and perhaps a primary change in cataractogenesis. The later changes in both beta and gamma may be secondary although they are certainly at least associated with cataractogenesis. The invariable decrease in gamma with age is noticeably accelerated in cataractogenesis.