title: Intra-membrane signaling between the voltage-gated Ca2+-channel and cysteine residues of syntaxin 1A coordinates synchronous release.
abstract: The interaction of syntaxin 1A (Sx1A) with voltage-gated calcium channels (VGCC) is required for depolarization-evoked release. However, it is unclear how the signal is transferred from the channel to the exocytotic machinery and whether assembly of Sx1A and the calcium channel is conformationally linked to triggering synchronous release. Here we demonstrate that depolarization-evoked catecholamine release was decreased in chromaffin cells infected with semliki forest viral vectors encoding Sx1A mutants, Sx1A(C271V), or Sx1A(C272V), or by direct oxidation of these Sx1A transmembrane (TM) cysteine residues. Mutating or oxidizing these highly conserved Sx1A Cys271 and Cys272 equally disrupted the Sx1A interaction with the channel. The results highlight the functional link between the VGCC and the exocytotic machinery, and attribute the redox sensitivity of the release process to the Sx1A TM C271 and C272. This unique intra-membrane signal-transduction pathway enables fast signaling, and triggers synchronous release by conformational-coupling of the channel with Sx1A.
authors.affiliation: The Hebrew University of Jerusalem, Institute of Life Sciences, Department of Biological Chemistry, Givat-Ram, Jerusalem, Israel.
authors.forename: Niv
authors.initials: N
authors.lastname: Bachnoff
authors.forename: Moshe
authors.initials: M
authors.lastname: Cohen-Kutner
authors.forename: Michael
authors.initials: M
authors.lastname: Trus
authors.forename: Daphne
authors.initials: D
authors.lastname: Atlas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism*; D019439:Chromaffin Cells / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism*; D005089:Exocytosis; D015870:Gene Expression; D006801:Humans; D008564:Membrane Potentials; D008954:Models, Biological; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010084:Oxidation-Reduction; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction; D050827:Syntaxin 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D020746:Calcium Channels, L-Type; C419385:L-type calcium channel alpha(1C); D050827:Syntaxin 1; D003545:Cysteine