Modifications of SNAP25

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Modifications of SNAP25
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Oxidation

• SNAP25 is a presynaptic target for the
  depressant action of reactive oxygen species on
  transmitter release
• Hydrogen Peroxide is a mild oxidant that can
  modify cysteine, methionine or tyosine groups of
  proteins

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• Addition of divalent iron promotes the Fenton
  Reaction, transforming peroxide into the highly
  reactive hydroxyl radical

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• Evoked release, not dependent on calcium
  channels.
• Hydrogen peroxide still decreases the frequency
  of MEPPs

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• Oxidation decreases complex formation

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• SNAP25 is most sensitive to oxidation

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Palmitoylation

• Palmitoylation involves the attachment of the 16
  carbon saturated fatty acid palmitate to specific
  cysteines via thioester linkage.
• Palmitoylation is reversible, making it a
  potentially dynamic posttranslational mechanism
  for regulating proteins

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Other Modifications

• SNAP25a is also an iron-sulfur protein
• SNAP25 is cleaved by Botulinum neurotoxins