Specificity and regulation of a synaptic vesicle docking complex.
Synaptic vesicles are proposed to dock at the presynaptic plasma membrane through the interaction of two integral membrane proteins of synaptic vesicles, VAMP and synaptotagmin, and two plasma membrane proteins, syntaxin and SNAP-25. We have characterized the binding properties of these proteins and observed SNAP-25 potentiation of VAMP 2 binding to syntaxins 1a and 4 but not syntaxins 2 or 3. n-sec1, a neuron-specific syntaxin-binding protein, bound syntaxin with nanomolar affinity, forming a complex that is distinct from the previously identified 7S and 20S syntaxin-containing complexes. This suggests that syntaxin exists in at least three states: bound to n-sec1, in a 7S particle, and in a 20S particle. Recombinant n-sec1 inhibited VAMP or SNAP-25 binding to syntaxin. We propose that the specific associations of VAMP, SNAP-25, and syntaxin mediate vesicle docking and that a syntaxin/n-sec1 complex precedes and/or regulates formation of these complexes.
Pevsner
J
J
Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical Center, California 94305.
Hsu
S C
SC
Braun
J E
JE
Calakos
N
N
Ting
A E
AE
Bennett
M K
MK
Scheller
R H
RH
D000595:Amino Acid Sequence; D000818:Animals; D005089:Exocytosis; D005656:Fungal Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D050683:R-SNARE Proteins; D051381:Rats; D011993:Recombinant Fusion Proteins; D013572:Synaptic Vesicles / Q000502:physiology*; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins
D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins