Pyruvate dehydrogenase is a catalyst for an irreversible step in the degradation of glucose and its activity is regulated by a highly specific protein kinase, pyruvate dehydrogenase kinase (PDHK/PDK). PDHK belongs to a family of mitochondrial protein kinases unique from other eukaryotic protein kinases. PDHK inactivates the multienzyme mitochondrial pyruvate dehydrogenase complex by the phosphorylation of three seryl residues in the pyruvate dehydrogenase moiety, and thus plays an important role in the control of glucose homeostasis.
There are four isoforms of PDHK (1 to 4) in humans. PDHK isoforms are up-regulated in obesity, diabetes, heart failure, and cancer and are potential therapeutic targets for these important human diseases.