Phosphorylation of pig brain diacylglycerol kinase by endogenous protein kinase

Abstract

Pig brain diacylglycerol kinase did not catalyze autophosphorylation. However, the kinase was phosphorylated on serine, when immunoprecipitated from the partially purified enzyme preparation preincubated with Mg²⁺ and [γ-³²P]ATP. The action of the endogenous protein kinase phosphorylating diacylglycerol kinase was independent of cyclic nucleotides and Ca²⁺, and became maximum at pH 5.5. Although the extent of enzyme phosphorylation was limited (maximally about 0.25 mol P_i incorporated per mol kinase), the results show that diacylglycerol kinase can be a phosphoprotein.