Snares for GLUT4--mechanisms directing vesicular trafficking of GLUT4

Fusion of GLUT4 vesicles with the plasma membrane is a key terminal step in insulin-regulated glucose transport. This fusion event is mediated by SNARE proteins, syntaxin 4, SNAP23 and VAMP2, through a process regulated by accessory proteins whose roles are still unclear. Munc18c is a key regulatory protein of syntaxin, and possibly of whole-SNARE complex cycling. Rab GTPases, through interactions with tethering molecules and SNAREs, provide targeting specificity in the GLUT4 secretory pathway. We review here insulin-mediated signaling of glucose transport, and particularly the role played by SNAREs and their accessory proteins.