Martinez-Arca, S., Rudge, R., Vacca, M., Raposo, G., Camonis, J., Proux-Gillardeaux, V., Daviet, L., Formstecher, E., Hamburger, A., Filippini, F., D'Esposito, M., Galli, T. (2003). A dual mechanism controlling the localization and function of exocytic v-SNAREs.  Proc. Natl. Acad. Sci. U.S.A. 100(15): 9011--9016.

FBrf0159723

Research paper

SNARE [soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptor] proteins are essential for membrane fusion but their regulation is not yet fully understood. We have previously shown that the amino-terminal Longin domain of the v-SNARE TI-VAMP (tetanus neurotoxin-insensitive vesicle-associated membrane protein)/VAMP7 plays an inhibitory role in neurite outgrowth. The goal of this study was to investigate the regulation of TI-VAMP as a model of v-SNARE regulation. We show here that the Longin domain (LD) plays a dual role. First, it negatively regulates the ability of TI-VAMP and of a Longin/Synaptobrevin chimera to participate in SNARE complexes. Second, it interacts with the adaptor complex AP-3 and this interaction targets TI-VAMP to late endosomes. Accordingly, in mocha cells lacking AP-3 delta, TI-VAMP is retained in an early endosomal compartment. Furthermore, TI-VAMPc, an isoform of TI-VAMP lacking part of the LD, does not interact with AP-3, and therefore is not targeted to late endosomes; however, this shorter LD still inhibits SNARE-complex formation. These findings support a mechanism controlling both localization and function of TI-VAMP through the LD and clathrin adaptors. Moreover, they point to the amino-terminal domains of SNARE proteins as multifunctional modules responsible for the fine tuning of SNARE function.

PMC166429 (PMC) (EuropePMC)