Required for anchoring dihydrolipoamide dehydrogenase (E3) to the dihydrolipoamide transacetylase (E2) core of the pyruvate dehydrogenase complexes of eukaryotes. This specific binding is essential for a functional PDH complex (By similarity). Part of the inner core of the multimeric pyruvate dehydrogenase complex that is composed of about 48 DLAT and 12 PDHX molecules. This core binds multiple copies of pyruvate dehydrogenase (subunits PDH1A and PDHB, E1), dihydrolipoamide acetyltransferase (DLAT, E2) and lipoamide dehydrogenase (DLD, E3). Interacts with SIRT4. Interacts with DLD. Delipoylated at Lys-97 by SIRT4, delipoylation decreases the PHD complex activity. Belongs to the 2-oxoacid dehydrogenase family.