Translocation of nuclear encoded preproteins into the mitochondrial matrix requires the coordinated action of the translocases Tom and Tim, which are located in the outer mitochondrial membrane and the inner membrane, respectively. The mitochondrial preprotein translocases of the outer membrane (Tom) is a multi-subunit protein that contains at least eight proteins: four import receptor subunits (Tom70, Tom37, Tom22, and Tom20), three small proteins (Tom7, Tom6, and Tom5), and a structural component of the outer membrane channel (Tom40). The Tom machinery involves the import receptors, which initiate the binding of cytosolically synthesized preproteins to the outer membrane, and a general import pore (GIP), which promotes the translocation of various pre-proteins into the mitochondria. The TIM channel imports nuclear-encoded mitochondrial preproteins, and it involves three proteins, Tim17, Tim23 and Tim44, which are represented at equimolar ratios. Tim17 is expressed as two isoforms Tim17a and Tim17b, which differ only in their C termini sequences, and like Tim23, these proteins are ubiquitously expressed in fetal and adult tissues. Tim17 and Tim23 are integral membrane proteins that comprise the structural elements of the inner membrane channel by which the preproteins are transferred. The Tim44, on the other hand, is a largely hydrophilic protein that recruits the matrix located Hsp70 to the site where the preprotein emerges from the Tim channel.
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Protein Aliases: Inner membrane preprotein translocase Tim17a; Mitochondrial import inner membrane translocase subunit Tim17-A; mitochondrial inner membrane translocase; preprotein translocase; translocase of inner mitochondrial membrane 17a; translocator of inner mitochondrial membrane 17 kDa, a; translocator of inner mitochondrial membrane 17a; translocator of inner mitochondrial membrane a
Gene Aliases: 17kDa; MIMT17; mTim17a; TIM17; TIM17A; TIMM17; TIMM17A
Molecular Function: transporter