Vamp7

VAMP7 is also called synaptobrevin-like gene 1 protein and tetanus-neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP). Sybl1 was the first pseudoautosomal gene found to be X and Y inactivated. TI-VAMP/VAMP7 is a vesicular SNARE protein. TI-VAMP/VAMP7 is involved in transport to lysosomes in fibroblasts, lysosomal secretion in fibroblasts and macrophages, endosomal exocytosis in adipocytes, and neuritogenesis in neuronal cells. In contrast to 'brevin' v-SNAREs such as synaptobrevin 2/VAMP2 and cellubrevin/VAMP3, TI-VAMP/VAMP7 is resistant to clostridial neurotoxins (tetanus and botulinum neurotoxins B, D, F, and G); the insensitivity of TI-VAMP to botulinum neurotoxin B relies on at least 12 amino-acid changes from the sequence of synaptobrevin 2/VAMP2. TI-VAMP/VAMP7 is the prototype of 'longin' v-SNARE, the longin domain being an amino-terminal extension of about 100 amino acids. Longins also include the v-SNAREs Ykt6p and Sec22p. In TI-VAMP/VAMP7, the longin domain has two functions: it binds to the ? subunit of the molecular coat AP-3 protein to target TI-VAMP/VAMP7 to late endosomes, and it inhibits the formation of SNARE complexes. TI-VAMP/VAMP7 interacts with plasma membrane and endosomal target SNAREs.