Inhibits the mitochondrial pyruvate dehydrogenase complex by phosphorylation of the E1 alpha subunit (PDA1), thus contributing to the regulation of glucose metabolism. Also involved in telomere maintenance. ATP + L-seryl-[pyruvate dehydrogenase E1 alpha subunit] = ADP + H(+) + O-phospho-L-seryl-[pyruvate dehydrogenase E1 alpha subunit] Interacts with PKP2. Present with 4220 molecules/cell in log phase SD medium. Belongs to the PDK/BCKDK protein kinase family.