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. Part of the inner core of the multimeric pyruvate dehydrogenase complex that is composed of about 48 DLAT and 12 PDHX molecules (PubMed:14638692, PubMed:20361979). This core binds multiple copies of pyruvate dehydrogenase (subunits PDH1A and PDHB, E1), dihydrolipoamide acetyltransferase (DLAT, E2) and lipoamide dehydrogenase (DLD, E3) (PubMed:14638692). Interacts with SIRT4 (PubMed:25525879). Interacts with DLD (PubMed:20385101, PubMed:16263718, PubMed:16442803, PubMed:20160912, PubMed:20361979). Delipoylated at Lys-97 by SIRT4, delipoylation decreases the PHD complex activity. The disease is caused by variants affecting the gene represented in this entry. Belongs to the 2-oxoacid dehydrogenase family.