The pyruvate dehydrogenase complex catalyzes the overall conversion of pyruvate to acetyl-CoA and CO(2). It contains multiple copies of three enzymatic components: pyruvate dehydrogenase (E1), dihydrolipoamide acetyltransferase (E2) and lipoamide dehydrogenase (E3). (R)-N(6)-lipoyl-L-lysyl-[dihydrolipoyllysine-residue acetyltransferase] + H(+) + pyruvate = (R)-N(6)-(S(8)-acetyldihydrolipoyl)-L-lysyl-[dihydrolipoyllysine-residue acetyltransferase] + CO2 E1 activity is regulated by phosphorylation (inactivation) and dephosphorylation (activation) of the alpha subunit. Tetramer of 2 alpha and 2 beta subunits. Reduced sensitivity to several IAA-amino acid conjugates.