Protein components of rat lens and their age-related changes observed with two-dimensional polyacrylamide gel electrophoresis

The protein components of rat lens crystallins were analyzed by two-dimensional urea-sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The following age-related changes were observed. (i) In alpha-crystallin, one or two spots at the anodic sides of alpha A2 and alpha B2 spots were observed in the lens cortex after the 8 months. beta-Crystallin, consisting of seven components designated as beta-1 to beta-7 components in the case of 1.5-month-old rats, showed marked changes during ageing. Component beta-3 was not detectable in neonatal lens. Component beta-5' located at the cathodic side of component beta-5 was observed in the lens older than 8 months. Components at the anodic sides of beta-4, beta-6 and beta-7 spots were detected in 8-month and especially 19- and 47-month-old lenses. The amount of gamma-crystallin decreased in dependence on age. (ii) The electrophoretogram of the nucleus of 8-month-old lens showed additional spots in the area with the lower molecular weight than alpha A2. gamma-Crystallin was accumulated in the nucleus. The electrophoretogram of gamma-crystallin of the 8-month-old nucleus was more similar to that of 19-month-old lens cortex than that of neonatal lens or young lens cortex.