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Differential Phosphorylation of Syntaxin and Synaptosome‐Associated Protein of 25 kDa (SNAP‐25) Isoforms
Author(s) -
Risinger Carl,
Bennett Mark K.
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.0720614.x
Subject(s) - syntaxin 3 , microbiology and biotechnology , syntaxin , snap23 , stx1a , synaptotagmin 1 , synaptic vesicle , biology , protein phosphorylation , synaptobrevin , phosphorylation , munc 18 , protein kinase a , exocytosis , chemistry , biochemistry , membrane protein , vesicle , vesicle associated membrane protein 8 , membrane
: The synaptic plasma membrane proteins syntaxin andsynaptosome‐associated protein of 25 kDa (SNAP‐25) are central participants insynaptic vesicle trafficking and neurotransmitter release. Together with thesynaptic 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 attachmentprotein (α‐SNAP). Consequently, syntaxin, SNAP‐25, and VAMP (and theirisoforms in other membrane trafficking pathways) have been termed SNAPreceptors (SNAREs). Because protein phosphorylation is a common and importantmechanism for regulating a variety of cellular processes, including synaptictransmission, we have investigated the ability of syntaxin and SNAP‐25isoforms to serve as substrates for a variety of serine/threonine proteinkinases. Syntaxins 1A and 4 were phosphorylated by casein kinase II, whereassyntaxin 3 and SNAP‐25 were phosphorylated by Ca 2+ ‐ andcalmodulin‐dependent protein kinase II and cyclic AMP‐dependent proteinkinase, respectively. The biochemical consequences of SNARE proteinphosphorylation included a reduced interaction between SNAP‐25 andphosphorylated syntaxin 4 and an enhanced interaction between phosphorylatedsyntaxin 1A and the synaptic vesicle protein synaptotagmin I, a potentialCa 2+ 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 α‐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.