Use of a novel method to find substrates of protein kinase C delta identifies M2 pyruvate kinase

Protein kinase C (PKC) family members have been implicated in numerous cellular processes. However, identifying the substrates of each PKC isozyme remains a challenge. Here, we describe a method using two-dimensional (2D) isoelectric focusing gel electrophoresis to identify substrates of delta PKC (δPKC) in MCF-7 breast carcinoma cells. We show that M2 pyruvate kinase is a substrate of δPKC, and further characterize the interaction between M2 pyruvate kinase and δPKC in MCF-7 cells by immunoprecipitation. δPKC activation in vitro or in cells did not appear to alter the enzyme activity or polymerization of M2 pyruvate kinase.