Functional impact of syntaxin on gating of N-type and Q-type calcium channels

Nature. 1995 Dec 7;378(6557):623-6. doi: 10.1038/378623a0.


Rapid and reliable synaptic transmission depends upon the close proximity of voltage-gated calcium channels and neurotransmitter-containing vesicles in the presynaptic terminal. Although it is clear that a local Ca2+ rise conveys the crucial signal from Ca2+ channels to the exocytotic mechanism, little is known about whether communication ever proceeds in the opposite direction, from the release machinery to Ca2+ channels. To look for such signalling, we examined the interaction of various types of voltage-gated Ca2+ channels with syntaxin, a presynaptic membrane protein of relative molecular mass 35,000 which may play a key part in synaptic vesicle docking and fusion and which interacts strongly with N-type Ca2+ channels. Here we report that co-expression of syntaxin 1A with N-type channels in Xenopus oocytes sharply decreases the availability of these channels. This is due to the stabilization of channel inactivation rather than to a simple block or lack of channel expression, because it is overcome by strong hyperpolarization. Deletion of syntaxin's carboxy-terminal transmembrane domain abolishes its functional effect on Ca2+ channels. Syntaxin produced a similar effect on Q-type Ca2+ channels encoded by alpha 1A but not on L-type Ca2+ channels. Thus, the syntaxin effect is specific for Ca2+ channel types that participate in fast transmitter release in the mammalian central nervous system. We hypothesize that, in addition to acting as a vesicle-docking site, syntaxin may influence presynaptic Ca2+ channels, opposing Ca2+ entry where it is not advantageous, but allowing it at release sites where synaptic vesicles have become docked and/or ready for fusion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Surface / chemistry
  • Antigens, Surface / genetics
  • Antigens, Surface / physiology*
  • Calcium / metabolism
  • Calcium Channels / metabolism*
  • Ion Channel Gating*
  • Membrane Potentials
  • Mutation
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / physiology*
  • Oocytes
  • RNA, Complementary / genetics
  • Synaptic Vesicles / metabolism
  • Syntaxin 1
  • Xenopus


  • Antigens, Surface
  • Calcium Channels
  • Nerve Tissue Proteins
  • RNA, Complementary
  • Syntaxin 1
  • Calcium