Component of the pyruvate dehydrogenase (PDH) complex, that catalyzes the overall conversion of pyruvate to acetyl-CoA and CO(2). (R)-N(6)-dihydrolipoyl-L-lysyl-[protein] + acetyl-CoA = (R)-N(6)-(S(8)-acetyldihydrolipoyl)-L-lysyl-[protein] + CoA Binds 2 lipoyl cofactors covalently. Forms a 24-polypeptide structural core with octahedral symmetry. Part of the PDH complex, consisting of multiple copies of AceE (E1), DlaT (E2) and Lpd (E3). Belongs to the 2-oxoacid dehydrogenase family.