Figure 4

4A mutation causes defect in fusion of GLUT4-containing vesicles at the plasma membrane. 3T3-L1 adipocytes transfected with wild type (WT, black bars) or 4A mutant (MUT, grey bars) pGLUT4HA-GFP. Cells were serum-starved for 4 hr prior to stimulation with 83 nM insulin for 30 min. The ratio of Alexa633 to GFP signals at the plasma membrane was quantified as described in Materials and Methods. Histogram (a) shows distribution of ratios for wild type and mutant GLUT4-expressing cells expressed as a % of the total in each condition, and is representative of 3 independent experiments. Graph (b) shows means of 3 independent experiments ± SEM. The difference between wild type and mutant mean values is statistically significant (t-test P < 0.05, ANOVA P < 0.0005).