Differential phosphorylation of syntaxin and synaptosome-associated protein of 25 kDa (SNAP-25) isoforms

J Neurochem. 1999 Feb;72(2):614-24. doi: 10.1046/j.1471-4159.1999.0720614.x.

Abstract

The synaptic plasma membrane proteins syntaxin and synaptosome-associated protein of 25 kDa (SNAP-25) are central participants in synaptic vesicle trafficking and neurotransmitter release. Together with the synaptic vesicle protein synaptobrevin/vesicle-associated membrane protein (VAMP), they serve as receptors for the general membrane trafficking factors N-ethylmaleimide-sensitive factor (NSF) and soluble NSF attachment protein (alpha-SNAP). Consequently, syntaxin, SNAP-25, and VAMP (and their isoforms in other membrane trafficking pathways) have been termed SNAP receptors (SNAREs). Because protein phosphorylation is a common and important mechanism for regulating a variety of cellular processes, including synaptic transmission, we have investigated the ability of syntaxin and SNAP-25 isoforms to serve as substrates for a variety of serine/threonine protein kinases. Syntaxins 1 A and 4 were phosphorylated by casein kinase II, whereas syntaxin 3 and SNAP-25 were phosphorylated by Ca2+- and calmodulin-dependent protein kinase II and cyclic AMP-dependent protein kinase, respectively. The biochemical consequences of SNARE protein phosphorylation included a reduced interaction between SNAP-25 and phosphorylated syntaxin 4 and an enhanced interaction between phosphorylated syntaxin 1A and the synaptic vesicle protein synaptotagmin I, a potential Ca2+ sensor in triggering synaptic vesicle exocytosis. No other effects on the formation of SNARE complexes (comprised of syntaxin, SNAP-25, and VAMP) or interactions involving n-Sec1 or alpha-SNAP were observed. These findings suggest that although phosphorylation does not directly regulate the assembly of the synaptic SNARE complex, it may serve to modulate SNARE complex function through other proteins, including synaptotagmin I.

Publication types

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

MeSH terms

  • Animals
  • Antigens, Surface / metabolism*
  • Binding Sites / physiology
  • Calcium-Binding Proteins*
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Carrier Proteins / chemistry
  • Carrier Proteins / metabolism
  • Casein Kinase II
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Exocytosis / physiology
  • Isomerism
  • Membrane Glycoproteins / metabolism
  • Membrane Proteins / metabolism
  • Mice
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / metabolism*
  • Neurons / chemistry
  • Neurons / cytology
  • Neurons / enzymology
  • Phosphorylation
  • Protein Kinase C / metabolism
  • Protein-Serine-Threonine Kinases / metabolism
  • Qa-SNARE Proteins
  • Qb-SNARE Proteins
  • Qc-SNARE Proteins
  • R-SNARE Proteins
  • Rats
  • SNARE Proteins
  • Synaptosomal-Associated Protein 25
  • Synaptosomes / chemistry
  • Synaptosomes / enzymology*
  • Synaptotagmin I
  • Synaptotagmins
  • Syntaxin 1
  • Vesicular Transport Proteins*

Substances

  • Antigens, Surface
  • Calcium-Binding Proteins
  • Carrier Proteins
  • Membrane Glycoproteins
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Qa-SNARE Proteins
  • Qb-SNARE Proteins
  • Qc-SNARE Proteins
  • R-SNARE Proteins
  • SNAP23 protein, human
  • SNARE Proteins
  • STX1A protein, human
  • Snap23 protein, mouse
  • Snap25 protein, mouse
  • Snap25 protein, rat
  • Stx1a protein, mouse
  • Stx1a protein, rat
  • Synaptosomal-Associated Protein 25
  • Synaptotagmin I
  • Syntaxin 1
  • Syt1 protein, mouse
  • Syt1 protein, rat
  • Vesicular Transport Proteins
  • Synaptotagmins
  • Casein Kinase II
  • Protein-Serine-Threonine Kinases
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases