Components of the TIM complex facilitate the translocation of proteins across the inner membrane and into the mitochondrial matrix.
At the opening of the TIM17-23 complex, Tim44 recruits mitochondrial heat shock protein 70, which further mediates translocation of the precursor through ATP hydrolysis.
The function of Tim18 is not yet clear; however it is believed to play a role in assembly and stabilisation of the TIM22 complex, although is not involved in protein insertion into the membrane.
[6] Unlike cleavable preproteins, following translocation across the outer membrane via the translocase of the outer membrane, carrier preproteins are bound by the soluble Tim9-Tim10 complex of which the majority of this complex (~95%) is free floating within the intermembrane space.
However this membrane potential-dependent process takes place in absence of ATP-driven machinery.