Figure 3.

Myr-Akt1 mimics insulin's effect on intracellular GLUT4. (A) Cartoon of GLUT4 trafficking. In basal cells, GLUT4 is equally distributed between endosomes and a specialized compartment because it rapidly cycles intracellularly between these compartments. Insulin simulated efflux of GLUT4 to the cell surface correlates with a redistribution of intracellular GLUT4 to endosomes (Karylowski et al., 2004). (B) Summary of 12 independent ablation experiments in 3T3-L1 adipocytes in the basal and insulin-stimulated state (means ± SEM). The nonablatable fraction is the amount of intracellular GLUT4 that is inaccessible to the TR expressed as a fraction of that accessible to IRAP-TR (Zeigerer et al., 2002; Karylowski et al., 2004). We refer to this nonablatable fraction as the pool of GLUT4 in the specialized compartment, as discussed in the introduction. (C) Results from a single experiment in cells coexpressing myr-Akt1 in the basal state. The data are from 25 cells for each condition.