The Tyrosine Phosphorylation and Cytoskeletal Translocation of Phospholipase C 1 in Bovine Adrenal Medullary Chromaffin Cells

Abstract

The tyrosine phosphatase inhibitor BpV(phen) stimulated a concentration-dependent increase of phospholipase C (PLC) activity in bovine adrenal medullary chromaffin cells. This response was accompanied by an increase in PLCgamma1 tyrosine phosphorylation and its cytosketetal translocation. Insulin, at high concentrations, stimulated PLC activity to a similar extent as BpV(phen), a response that was also accompanied by an increase in PLCgamma1 translocation but not its tyrosine phosphorylation. BpV(phen) strongly enhanced the insulin-stimulated increase in PLC activity and caused a small rise in PLCgamma1 translocation above that seen with insulin alone. Despite the synergistic rise in activity PLCgamma1 tyrosine phosphorylation did not increase beyond that seen with BpV(phen) alone. These results indicate that PLCgamma1 activation in chromaffin cells may be more closely associated with its cytoskeletal translocation than its tyrosine phosphorylation although other factors may also be important for activation of enzyme activity.