Insulin, in the presence of phorbol esters, was observed to stimulate the tyrosine phosphorylation of a major 80 kDa protein by immunoblotting with anti-phosphotyrosine antibodies in Chinese hamster ovary cells overexpressing the insulin receptor and protein kinase Cα. The protein was specifically immunoprecipitated by antibodies to protein kinase C and anti-phosphotyrosine antibodies were capable of immunoprecipitating protein kinase C enzymatic activity from these cells. When this tyrosine phosphorylated protein kinase C was treated with a tyrosine-specific phosphatase, a 35% decrease in its enzymatic activity was observed and this inhibition was blocked by inclusion of a tyrosine phosphatase inhibitor, vanadate, in the reaction mixture. These results indicate that under certain conditions insulin can stimulate the tyrosine phosphorylation of protein kinase C and this phosphorylation can affect its enzymatic activity.
|Original language||English (US)|
|Number of pages||8|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - May 15 1994|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology