The plasma membrane of the rabbit lens cortical fiber. I. Isolation, characterization, and biosynthesis of two membrane intrinsic polypeptides.

Rabbit lens cortical fiber plasma membrane polypeptides were isolated and two membrane intrinsic proteins were characterized by SDS-PAGE. A polypeptide with a molecular weight of 26 kilodaltons is the major constituent of the plasma membrane. The molecular weight and antigenic properties of the other polypeptide studied are similar to polypeptides of cortical water-soluble alpha-crystalline. Biosynthesis of these two polypeptides was studied. After initially high rates, synthesis of both of these polypeptides decreased considerably and maintained a steady rate for the rest of the culture time.