Kinase that plays a key role in the regulation of glucose and fatty acid metabolism and homeostasis via phosphorylation of the pyruvate dehydrogenase subunits PDHA1 and PDHA2. This inhibits pyruvate dehydrogenase activity, and thereby regulates metabolite flux through the tricarboxylic acid cycle, down-regulates aerobic respiration and inhibits the formation of acetyl-coenzyme A from pyruvate. Inhibition of pyruvate dehydrogenase decreases glucose utilization and increases fat metabolism. Mediates cellular responses to insulin. Plays an important role in maintaining normal blood glucose levels and in metabolic adaptation to nutrient availability. Via its regulation of pyruvate dehydrogenase activity, plays an important role in maintaining normal blood pH and in preventing the accumulation of ketone bodies under starvation. Plays a role in the regulation of cell proliferation and in resistance to apoptosis under oxidative stress. Plays a role in p53/TP53-mediated apoptosis. ATP + L-seryl-[pyruvate dehydrogenase E1 alpha subunit] = ADP + H(+) + O-phospho-L-seryl-[pyruvate dehydrogenase E1 alpha subunit] Activity increases in response to increased acetyl-CoA and NADH levels and upon binding to the pyruvate dehydrogenase subunit DLAT. Inhibited by ADP and pyruvate; these compounds interfere with DLAT binding and thereby inhibit kinase activity. Inhibited by dichloroacetate. Inhibited by AZD7545; this compound interferes with DLAT binding and thereby inhibits kinase activity. Reactive oxygen species cause the formation of disulfide bonds, and thereby inhibit the enzyme. Homodimer, and heterodimer with PDK1. Interacts with the pyruvate dehydrogenase complex subunit DLAT, and is part of the multimeric pyruvate dehydrogenase complex that contains multiple copies of pyruvate dehydrogenase (E1), dihydrolipoamide acetyltransferase (DLAT, E2) and lipoamide dehydrogenase (DLD, E3). Detected in heart (at protein level). Highest level of expression in heart and skeletal muscle and the lowest in spleen and lung. Liver, kidney, brain and testis levels are intermediate. Belongs to the PDK/BCKDK protein kinase family.