| SNIP (SNAP25-interacting protein)/p140Cap (p130Cas-associated protein) is a cytoskeleton-associated protein identified initially in rat as a protein interacting with the brain-specific synaptosome protein SNAP25 (1) and subsequently as interacting with the broadly expressed scaffold protein p130Cas (2). SNAP25, a presynaptic protein implicated in neurotransmitter secretion, membrane fusion and neurite outgrowth, is part of the SNARE complex that includes syntaxin and synaptobrevin/VAMP (3). SNIP-SNAP25 association is mediated by coiled-coil interactions (1). Overexpression of SNIP inhibits calcium-dependent exocytosis in PC12 cells (1). Human and mouse orthologs of SNIP, termed p140Cap, were subsequently identified through association with p130Cas, a substrate of v-Src and v-Crk that is tyrosine-phosphorylated in response to cell adhesion and mitogenic stimuli (2,4,5). Expression of p140Cap was observed in brain, testis and epithelial-rich tissues and may exist in various alternatively spliced, tissue-specific isoforms (2). p140Cap is also tyrosine-phosphoryalated in response to adhesion molecules and EGF treatment (2). Together these studies suggest a role for SNIP/p140Cap in controlling cell spreading, migration and neurosecretion. |
