Synip (Syntaxin 4-Interacting protein) specifically binds to Syntaxin 4 and is uniquely expressed in muscle and adipose tissue. The binding interaction of Synip with syntaxin 4 is regulated by insulin, which also induces dissociation of the Synip-syntaxin 4 complex. Synip plays a role in the translocation of transport vesicles from the cytoplasm to the plasma membrane and functions as a positive regulator of insulin-stimulated GLUT4 translocation. Synip also competes with VAMP2 but Not SNAP23 for binding to Syntaxin 4 (1-3).
