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Publication Abstract from PubMed

Complexin prevents SNAREs from releasing neurotransmitters until an action potential arrives at the synapse. To understand the mechanism for this inhibition, we determined the structure of complexin bound to a mimetic of a prefusion SNAREpin lacking the portion of the v-SNARE that zippers last to trigger fusion. The 'central helix' of complexin is anchored to one SNARE complex, while its 'accessory helix' extends away at ~45 degrees and bridges to a second complex, occupying the vacant v-SNARE binding site to inhibit fusion. We expected the accessory helix to compete with the v-SNARE for t-SNARE binding but found instead that the interaction occurs intermolecularly. Thus, complexin organizes the SNAREs into a zigzag topology that, when interposed between the vesicle and plasma membranes, is incompatible with fusion.

Complexin cross-links prefusion SNAREs into a zigzag array.,Kummel D, Krishnakumar SS, Radoff DT, Li F, Giraudo CG, Pincet F, Rothman JE, Reinisch KM Nat Struct Mol Biol. 2011 Jul 24;18(8):927-33. doi: 10.1038/nsmb.2101. PMID:21785414^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.