BCKDK belongs to the PDK/BCKDK protein kinase family. It contains 1 histidine kinase domain. BCKDK catalyzes the phosphorylation and inactivation of the branched-chain alpha-ketoacid dehydrogenase complex, the key regulatory enzyme of the valine, leucine and isoleucine catabolic pathways. BCKDK is the key enzyme that regulates the activity state of the BCKD complex.