FIG. 8.

Polypeptide composition of GLUT4-containing vesicles isolated from peak 1 and peak 2. Intracellular membranes were isolated from 3T3-L1 adipocytes and subjected to either velocity sucrose gradient or iodixanol density gradient sedimentation. Fractions enriched in GLUT4 from either the sucrose gradient (SG) or the iodixanol gradient (peak 1 [Pk1] and peak 2 [Pk2]) were pooled and incubated with a GLUT4-specific antibody (1F8) or an irrelevant antibody (CTL) coupled to cellulose fibers. Immunoadsorbed vesicles were eluted with 0.2 M bicarbonate buffer (pH 11.0) and pelleted, and the eluted proteins or the relevant starting materials were subjected to SDS-PAGE and silver staining. The migration of molecular weight standards is indicated at the left hand side (numbers indicate masses).