CoxG has been shown, in Oligotropha carboxidovorans, to anchor the carbon monoxide (CO) dehydrogenase to the cytoplasmic membrane. The gene encoding CoxG is part of the Cox cluster (coxBCMSLDEFGHIK) located on a low-copy-number, circular, megaplasmid pHCG3. This cluster includes genes encoding subunits of CO dehydrogenase and several accessory components involved in the utilization of CO. This family belongs to the SRPBCC (START/RHO_alpha_C/PITP/Bet_v1/CoxG/CalC) domain superfamily of proteins that bind hydrophobic ligands. SRPBCC domains have a deep hydrophobic ligand-binding pocket and they bind diverse ligands.