pyruvate dehydrogenase complex GO:0045254 IMR:0001002 PDC The mammalian pyruvate dehydrogenase complex is built around a 60-subunit inner core of tightly but noncovalently associated dihydrolipoamide acetyltransferase subunits (E2). Pyruvate dehydrogenase (E1) is a heterotetrameric alpha2beta2 structure that binds noncovalently to an E1-binding domain on E2. Dihydrolipoamide dehydrogenase (E3) binds to the complex by way of an E3-binding protein (E3BP). Twelve E3-binding proteins anchor 12 E3 homodimers to each pyruvate dehydrogenase complex. If the regulatory proteins associated with the complex are not included, each pyruvate dehydrogenase complex is composed of 216 subunits (60 E2, 60 E1alpha, 60 E1beta, 12 E3BP, and 24 E3) that sum up to about 9.5 MD. molecule_role dehydrogenase