Kinase that plays a key role in 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. Plays an important role in cellular responses to hypoxia and is important for cell proliferation under hypoxia. Protects cells against apoptosis in response to hypoxia and oxidative stress. ATP + L-seryl-[pyruvate dehydrogenase E1 alpha subunit] = ADP + H(+) + O-phospho-L-seryl-[pyruvate dehydrogenase E1 alpha subunit] Activated by binding to the pyruvate dehydrogenase complex subunit DLAT. Strongly activated by NADH plus acetyl-coenzyme A. Inhibited by dichloroacetate. Homodimer, and heterodimer with PDK2. 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 pancreas islets (at protein level). Expressed predominantly in the heart. Up-regulated via the HIF1A signaling pathway in response to hypoxia. Down-regulated in response to prolonged fasting. Phosphorylated by constitutively activated ABL1, FGFR1, FLT3 and JAK2 (in vitro), and this may also occur in cancer cells that express constitutively activated ABL1, FGFR1, FLT3 and JAK2. Phosphorylation at Tyr-241 and Tyr-242 strongly increases kinase activity, while phosphorylation at Tyr-136 has a lesser effect (By similarity). Belongs to the PDK/BCKDK protein kinase family.