Figure 1.

Schematic overview of the three members of the 2-oxo acid dehydrogenase complex (OADHC) family. (a) Pyruvate dehydrogenase complexes (PDC) contain an icosahedral E2p core to which E1p and E3 proteins become recruited. Additionally to E2p, PDC contains an alternative core forming subunit (E3BP) which specifically recruits E3. By contrast, for (b) 2-oxoglutarate dehydrogenase complexes (OGDHC) and (c) branched-chain α-keto acid dehydrogenase complex (BCKDC), E1 and E3 are tethered around an octahedral E2 core. For clarity, only single instances of E1/E3 subunits are shown. For all three OADH members, PSBD in the E2 sequence (bottom row) have been proposed to play a key role in recruiting E1 and E3 subunits to the core [19]. For all family members, the LD is essential for the carboxylation of 2-oxo acids, as it transfers respective intermediates from E1 to E2 components. Of these three, only OGDHC functions directly within the TCA cycle.