Effects of Botulinum Neurotoxin a on Protein Phosphorylation in Synaptosomes
The phosphorylation of presynaptic proteins was examined in the presence of chlorpromazine using synaptic lysates derived from rat brain synaptosomes that had been preincubated with or without botulinum neurotoxin A. Chlorpromazine increased the phosphorylated state of a number of phosphoproteins with apparent molecular weights (Mrs) between 40 and 60 kilodaltons. The drug’s most prominent effect was a 2.5–3.5-fold increase in the incorporation of phosphate into a peptide of Mr~43 kilodaltons (pp43), as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. After preincubation with toxin, the chlorpromazine-promoted increase in the phosphorylated state of pp43 was inhibited in a concentration- and temperature-dependent manner.
KeywordsBotulinum Toxin Botulinum Neurotoxin Synaptic Plasma Membrane Krebs Ringer Buffer Botulinum Neurotoxin Type
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