nSec1 binds a closed conformation of syntaxin1A.
The Sec1 family of proteins is proposed to function in vesicle trafficking by forming complexes with target membrane SNAREs (soluble N-ethylmaleimide-sensitive factor [NSF] attachment protein [SNAP] receptors) of the syntaxin family. Here, we demonstrate, by using in vitro binding assays, nondenaturing gel electrophoresis, and specific neurotoxin treatment, that the interaction of syntaxin1A with the core SNARE components, SNAP-25 (synaptosome-associated protein of 25 kD) and VAMP2 (vesicle-associated membrane protein 2), precludes the interaction with nSec1 (also called Munc18 and rbSec1). Inversely, association of nSec1 and syntaxin1A prevents assembly of the ternary SNARE complex. Furthermore, using chemical cross-linking of rat brain membranes, we identified nSec1 complexes containing syntaxin1A, but not SNAP-25 or VAMP2. These results support the hypothesis that Sec1 proteins function as syntaxin chaperons during vesicle docking, priming, and membrane fusion.
Yang
B
B
Howard Hughes Medical Institute, Department of Molecular Physiology, Stanford University School of Medicine, Stanford, California 94305-5428, USA.
Steegmaier
M
M
Gonzalez
L C
LC
Scheller
R H
RH
D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D001905:Botulinum Toxins / Q000494:pharmacology; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D050683:R-SNARE Proteins; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D050600:SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins
D000954:Antigens, Surface; D008565:Membrane Proteins; D018832:Molecular Chaperones; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; D011994:Recombinant Proteins; D050600:SNARE Proteins; C494210:Snap25 protein, rat; C497939:Stxbp1 protein, rat; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins; D001905:Botulinum Toxins