Lenticular intermediate-sized filaments: biosynthesis and interaction with plasma membrane.

Abstract

EM features of the [calf] lens fiber plasma membrane-cytoskeleton complex suggest an intimate association between the intermediate-sized filaments (IF) and the lipid bilayer. Biochemicalanalysis of this complex reveals the occurrence of an appreciable amount of vimentin as a protein subunit of lenticular IF. Additional evidence for association between IF and membranes is provided by the observation that newly synthesized vimentin is associated with plasma membranes added to a reticulocyte lysate programmed with lens polyribosomes. Concomitantly .alpha.-crystalline polypeptide chains (.alpha.A2) are also found associated with the plasma membrane together with a hitherto unidentified 47-kDalton protein. Once associated with the lipid bilayer, the vimentin polypeptide resists urea treatment, suggesting that it has become an integral constituent associated with part of the membrane.