The PDHX gene encodes component X of the pyruvate dehydrogenase (PDH) complex. For a detailed description of the pyruvate dehydrogenase complex. The mammalian PDH complex differs from that in E. coli and from the other mammalian alpha-keto acid dehydrogenases by the presence of a 53-kD protein called protein X. Component X binds to the E3 component of the PDH complex.

The open reading frame encodes an 501-amino acid protein sequence that is 20% identical with that encoded by the yeast PDX1 gene and 40% identical with that encoded by the lipoacyltransferase component E2 of the PDH (E2), and includes a lipoyl-bearing domain. Sequence comparisons showed that the PDHX protein contains an E3-binding domain.