We have updated our privacy policy. If you have any question, contact us at privacy@scicrunch.org. Dismiss and don't show again

Searching across hundreds of databases

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

The C terminus of SNAP25 is essential for Ca(2+)-dependent binding of synaptotagmin to SNARE complexes.

The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins syntaxin and synaptosome-associated protein of 25 kDa (SNAP25) and the vesicle SNARE protein vesicle-associated membrane protein (VAMP) are essential for a late Ca(2+)-dependent step in regulated exocytosis, but their precise roles and regulation by Ca(2+) are poorly understood. Botulinum neurotoxin (BoNT) E, a protease that cleaves SNAP25 at Arg(180)-Ile(181), completely inhibits this late step in PC12 cell membranes, whereas BoNT A, which cleaves SNAP25 at Gln(197)-Arg(198), is only partially inhibitory. The difference in toxin effectiveness was found to result from a reversal of BoNT A but not BoNT E inhibition by elevated Ca(2+) concentrations. BoNT A treatment essentially increased the Ca(2+) concentration required to activate exocytosis, which suggested a role for the C terminus of SNAP25 in the Ca(2+) regulation of exocytosis. Synaptotagmin, a proposed Ca(2+) sensor for exocytosis, was found to bind SNAP25 in a Ca(2+)-stimulated manner. Ca(2+)-dependent binding was abolished by BoNT E treatment, whereas BoNT A treatment increased the Ca(2+) concentration required for binding. The C terminus of SNAP25 was also essential for Ca(2+)-dependent synaptotagmin binding to SNAP25. syntaxin and SNAP25.syntaxin.VAMP SNARE complexes. These results clarify classical observations on the Ca(2+) reversal of BoNT A inhibition of neurosecretion, and they suggest that an essential role for the C terminus of SNAP25 in regulated exocytosis is to mediate Ca(2+)-dependent interactions between synaptotagmin and SNARE protein complexes.

Pubmed ID: 10692432 RIS Download

Mesh terms: Animals | Botulinum Toxins | Botulinum Toxins, Type A | Calcium | Calcium-Binding Proteins | Cell Membrane | Exocytosis | Membrane Glycoproteins | Membrane Proteins | Nerve Tissue Proteins | Neurotoxins | Norepinephrine | PC12 Cells | Protein Binding | R-SNARE Proteins | Rats | SNARE Proteins | Synaptosomal-Associated Protein 25 | Synaptotagmins | Vesicular Transport Proteins

Research resources used in this publication

None found

Research tools detected in this publication

None found

Data used in this publication

None found

Associated grants

  • Agency: NIDDK NIH HHS, Id: DK25861
  • Agency: NIDDK NIH HHS, Id: DK40428
  • Agency: NIGMS NIH HHS, Id: GM07215

Publication data is provided by the National Library of Medicine ® and PubMed ®. Data is retrieved from PubMed ® on a weekly schedule. For terms and conditions see the National Library of Medicine Terms and Conditions.

We have not found any resources mentioned in this publication.