Tyrosine phosphorylation of PLC-gamma 1 induced by electroconvulsive shock in rat hippocampus.

ECS has been shown to increase PIP2 breakdown in rat brain, which suggested the possible activation of PLC-signal transduction system by ECS. When we examined the PLC-gamma 1 immunoprecipitated from rat hippocampal tissues after ECS, we found a rapid increase in phosphotyrosine of PLC-gamma 1, which reached peak at 10 minutes after ECS and returned to basal level after 2 hours. There was no change in the amount of PLC-gamma 1 proteins during that period. The tyrosine phosphorylation induced by ECS didn't affect the enzyme activity when assayed in vitro. These results suggested that ECS may activate PLC-gamma 1 by phosphorylation on tyrosine residue, but without changing enzyme activity itself.