Comparative two-dimensional electrophoretic analysis ofwater soluble proteins from bovine and murine lenses

Abstract

Total soluble proteins were prepared from the lenses of 40-day-old mice by standard methods andeluted from Sepharose 6B. The resulting elution profile consisted of five crystallin peaks the last two of which were incompletely resolved. The total water soluble proteins and proteins prepared from fraction pools corresponding to each of the five peaks were subjected to polyacrylamide gel electrophoresis in two dimensions. Twenty-two major subunits were identified, each of which could be assigned to one of the major crystallin classes. We had expected the five peaks to correspond to the α H -, α L -, β H -, β L -, and γ -crystallin classes, well documented in the bovine system. However, electrophoretic studies showed that the five murine peaks actually contained, in descending order of molecular weight, α H -, α L -, β L - and two forms of γ -crystallins. No β H component was found. For comparative purposes, we have also analysed by identical methods, the lens crystallins of 4-month-old calves. Elution of the bovine crystallins from Sepharose 6B yielded the five protein peaks of expected composition. The elution volumes of the α H -, α L -, and β L -murine crystallins were identical with those of the corresponding bovine crystallins and the two incompletely resolved murine peaks eluted in a region similar to that of the bovine γ -crystallins. However, no murine crystallins eluted at a position corresponding to that of the bovine β H -crystallins. Bovine soluble lens proteins examined by two-dimensional electrophoresis showed limited interspecific homology with similarly prepared proteins from murine lenses. Two-dimensional electrophoresis provides a powerful analytical tool for investigations on soluble lens proteins.