SNAREs in native plasma membranes are active and readily form core complexes with endogenous and exogenous SNAREs

• DOI: 10.1083/jcb.200203088
• Publication Date: 2002-09-18T18:04:15Z
• Authors: Thorsten Lang; Martin Margittai; Helmut Hölzler; Reinhard Jahn
• Keywords: SNAP25; Synaptobrevin; SNARE complex

During neuronal exocytosis, the vesicle-bound soluble NSF attachment protein (SNAP) receptor (SNARE) synaptobrevin 2 forms complexes with plasma membrane–bound SNAREs syntaxin 1A and SNAP25 to initiate fusion reaction. However, it is not known whether in native membrane are constitutively active or they unable enter SNARE unless activated before fusion. Here we used binding of labeled recombinant inside-out carrier supported sheets PC12 cells probe for activity endogenous SNAREs. Binding was specific, saturable, depended on presence membrane-resident partners. Our data show that virtually all 1 SNAP-25 highly reactive readily form exogenously added Furthermore, between were detectable when membranes freshly prepared, but slowly upon prolonged incubation vitro. We conclude downregulated by control proteins even if engaged events.