MOVING GLUT4 - THE BIOGENESIS AND TRAFFICKING OF GLUT4 STORAGE-VESICLES

The GLUT4 system in muscle and fat cells plays an important role in wh ole-body glucose homeostasis. Insulin stimulates the translocation of GLUT4 from an intracellular storage compartment to the cell surface. T he nature of this compartment remains largely unknown. We review recen t studies describing the biogenesis and molecular constituents of the GLUT4 storage compartment and conclude that it is segregated from the endosomal and biosynthetic pathways. Further, we present evidence to s uggest that the GLUT4 storage compartment moves directly to the plasma membrane in response to insulin and, hence, is analogous to small syn aptic vesicles in neurons. We propose that the GLUT4 storage compartme nt be referred to as GLUT4 storage vesicles or GSVs.