Serine protein kinase that inhibits the mitochondrial pyruvate dehydrogenase (PDH) complex (mtPDC) by phosphorylation of the E1 alpha subunit on Ser residues, thus contributing to the regulation of glucose metabolism. ATP + L-seryl-[pyruvate dehydrogenase E1 alpha subunit] = ADP + H(+) + O-phospho-L-seryl-[pyruvate dehydrogenase E1 alpha subunit] Treatment with the His-directed reagents diethyl pyrocarbonate (DEPC) and dichloro-(2,2*:6*,2(-terpyridine))-platinum(II) dihydrate inhibits kinase activity, including autophosphorylation. kcat is 0.55 sec(-1) with ATP as substrate (at pH 7.5, in PubMed:15629119). Optimum pH is 7-7.5. Homodimer. Expressed constitutively and ubiquitously. Autophosphorylated on Ser residues near N-terminus. Elevation of the mitochondrial pyruvate dehydrogenase (PDH) complex (mtPDC) activity. Altered vegetative growth with reduced accumulation of vegetative tissues, early flower development and shorter generation time. Increased seed oil content and seed weight at maturity. Belongs to the PDK/BCKDK protein kinase family.