InterPro domain: IPR039238

The mitochondrial import inner membrane translocase is a 70kDa, heterohexamer complex consisting of three copies of Tim8 (or Tim8A and/or Tim8B) and three copies of Tim13. The subunits are homologous. The complex is located in the mitochondrial intermembrane space [ 1 ]. It is required for the import and insertion of some multi-pass transmembrane proteins into the mitochondrial inner membrane and also for transport of beta-barrel precursors from the TOM complex to the sorting and assembly machinery (SAM complex) of the outer membrane [ 2 ]. The complex is more selective than the Tim9-Tim10 complex, and substrates include Tim23, SLC25A12/ARALAR1 and SLC25A13/ARALAR2 [ 2 ]. Tim8 and Tim13 are zinc-finger proteins [ 3 ]. Mutations in the human Tim8A gene cause Mohr-Tranebjaerg syndrome which is an X-linked recessive deafness syndrome associated with progressive visual deterioration, dystonia, dementia, and psychiatric abnormalities [ 3 ].

1. Role of the deafness dystonia peptide 1 (DDP1) in import of human Tim23 into the inner membrane of mitochondria. J. Biol. Chem. 276, 37327-34
2. The calcium-binding aspartate/glutamate carriers, citrin and aralar1, are new substrates for the DDP1/TIMM8a-TIMM13 complex. Hum. Mol. Genet. 13, 2101-11
3. Neuronal cell death in the visual cortex is a prominent feature of the X-linked recessive mitochondrial deafness-dystonia syndrome caused by mutations in the TIMM8a gene. Ophthalmic Genet. 22, 207-23