Figure 4.

Insertion of metabolite carriers into the inner mitochondrial membrane. The Tom70 receptor takes over metabolite carrier precursors from cytosolic chaperones. The precursors pass the outer membrane in a loop conformation. In the IMS, the hydrophobic transmembrane segments of carriers are shielded by the Tim9/Tim10 chaperone complex, which delivers the precursor to the TIM22 machinery in the inner membrane. Tim54 and the adaptor protein Tim12 transfer the precursor to the protein-conducting channel formed by Tim22. Tim18, and Sdh3 are required for assembly and stability of the translocase. The membrane potential across the inner mitochondrial membrane (Δψ) drives the insertion of metabolite carriers, which finally adopt their functional, dimeric state. OM, outer membrane; IMS, intermembrane space; IM, inner membrane.