InterPro domain: IPR039175

The membrane-embedded multi-protein complexes of mitochondria mediate the transport of nuclear-encoded proteins across and into the outer or inner mitochondrial membranes [ 1 ]. Two translocases of the inner mitochondrial membrane (TIM22 and TIM23 complexes) mediate protein transport at the inner membrane.

The TIM22 complex (a twin-pore carrier translocase) catalyses the insertion of multi-spanning proteins that have internal targeting signals into the inner membrane. The TIM22 complex mediates the membrane insertion of multi-spanning inner-membrane proteins that have internal targeting signals, and it uses the membrane potential as an external driving force [ 2 ]. The Tim22 subunit of the mitochondrial import inner membrane translocase is included in this family. Tim22 forms a hydrophilic, high-conductance channel with distinct opening states and pore diameters, that is voltage-activated and specifically responds to an internal targeting signal [ 3 ].

1. Mitochondrial import and the twin-pore translocase. Nat. Rev. Mol. Cell Biol. 5, 519-30
2. Import of carrier proteins into the mitochondrial inner membrane mediated by Tim22. Nature 384, 582-5
3. Tim22, the essential core of the mitochondrial protein insertion complex, forms a voltage-activated and signal-gated channel. Mol. Cell 9, 363-73