Role of estrogenic compounds (diethylstibestrol, 17β-estradiol, and bisphenol A) in the phosphorylation of substrate by protein kinase Cα

Estrogenic compounds can activate protein kinase C (PKC), which is a calcium and phospholipid-dependent serine/threonine kinase. In the present study, we investigated the role of 17β-estradiol (E2), diethylstibestrol (DES), and bisphenol A (BPA) in the phosphorylation of substrate by PKCα using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The level of phosphorylated peptide was low in the absence of phosphatidylserine (PS). Moreover, reduction of phosphorylation ratios was identified in the presence of diacylglycerol (DAG) and Ca²⁺ or PS and Ca²⁺ after adding E2, DES, and BPA. However, no change in phosphorylation ratios was found in the presence of DAGand PS. Addition of E2, DES, and BPA also had no influence on the phosphorylation reaction of substrate by cell or tissue lysate samples. Our study suggests that E2, DES, and BPA can bind to the C2 domain of PKCα but have no effects on the phosphorylation reaction of substrates in the presence of DAG and PS.