Open AccessInteraction of the synprint site of N-type Ca 2+ channels with the C2B domain of synaptotagmin I
Author(s) -
ZuHang Sheng,
Charles T. Yokoyama,
William A. Catterall
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.10.5405
Subject(s) - synaptotagmin 1 , syntaxin , synaptotagmin i , stx1a , exocytosis , neurotransmission , chemistry , synaptic vesicle , biophysics , microbiology and biotechnology , biochemistry , biology , receptor , vesicle , membrane
N-type Ca2+ channels mediate Ca2+ influx, which initiates fast exocytosis of neurotransmitters at synapses, and they interact directly with the SNARE proteins syntaxin and SNAP-25 (synaptosome-associated protein of 25 kDa) through asyn apticpr oteinint eraction (synprint) site in the intracellular loop connecting domains II and III of their α1B subunits. Introduction of peptides containing the synprint site into presynaptic neurons reversibly inhibits synaptic transmission, confirming the importance of interactions with this site in synaptic transmission. Here we report a direct interaction of the synprint peptide from N-type Ca2+ channels with synaptotagmin I, an important Ca2+ sensor for exocytosis, as measured by an affinity-chromatography binding assay and a solid-phase immunoassay. This interaction is mediated by the second C2 domain (C2B) of synaptotagmin I, but is not regulated by Ca2+ . Using both immobilized recombinant proteins and native presynaptic membrane proteins, we found that the synprint peptide and synaptotagmin competitively interact with syntaxin. This interaction is Ca2+ -dependent because of the Ca2+ dependence of the interactions between syntaxin and these two proteins. These results provide a molecular basis for a physical link between Ca2+ channels and synaptotagmin, and suggest that N-type Ca2+ channels may undergo a complex series of Ca2+ -dependent interactions with multiple presynaptic proteins during neurotransmission.