Mitochondrial inner membrane pre-sequence translocase complex

Species: yeast; 559292
Accession number: EBI-1205157


Systematic Name:


Tim23 complex Mitochondrial inner membrane translocase complex
Inner mitochondrial membrane presequence translocase Import inner membrane translocase
Bioactive entity
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Major preprotein translocase in the inner membrane of mitochondria, mediates the translocation of N-terminal, positively charged presequence-containing proteins. Proteins in which the charged sequence is followed by a hydrophobic sorting signal are laterally transferred and inserted into the inner membrane. and the hydrolysis of ATP. TIM50 interacts with incoming presequence-carrying preproteins as they reach the trans site of the TOM complex (EBI-1180520). Preproteins are directed by the intermembrane space-exposed domains of TIM21, TIM50, and TIM23 to the protein-conducting channel of the TIM23 complex. Translocation is energetically driven by the electrical membrane potential across the inner membrane where they interact with the ATP-bound state of SSC1 Upon ATP hydrolysis, SSC1 tightly binds the incoming chain and is released from the TIM23 complex. Repeated mtHsp70-binding cycles drive complete translocation of the precursor protein. mtHsp70 is finally released upon exchange of the bound ADP for ATP, a reaction stimulated by Mge1. In most cases, the presequence is proteolytically removed by the mitochondrial-processing peptidase (EBI-2313847).


The components of the TIM23 complex can be sub-divided into two groups, which appear to operate in a sequential and cooperative manner: the membrane protein-conducting channel (TIM50, TIM23, TIM21 and TIM17) and the import motor that drives the translocation into the matrix space (TIM44, PAM18, PAM16, SSC1and MGE11)


ID Name Description Stoichiometry Biological Role Interactor Type Other Features
TIM21 Mitochondrial import inner membrane translocase subunit TIM21 unspecified role protein
PAM16 Mitochondrial import inner membrane translocase subunit TIM16 unspecified role protein
TIM50 Mitochondrial import inner membrane translocase subunit TIM50 unspecified role protein
PAM18 Mitochondrial import inner membrane translocase subunit TIM14 unspecified role protein
MGE1 GrpE protein homolog, mitochondrial unspecified role protein
SSC1 Heat shock protein SSC1, mitochondrial unspecified role protein
TIM17 Mitochondrial import inner membrane translocase subunit TIM17 unspecified role protein
TIM23 Mitochondrial import inner membrane translocase subunit TIM23 unspecified role protein
TIM44 Mitochondrial import inner membrane translocase subunit TIM44 unspecified role protein

Cross References

Type Database Identifier Description
molecular function gene ontology GO:0015450 P-P-bond-hydrolysis-driven protein transmembrane transporter activity
cellular component gene ontology GO:0005744 mitochondrial inner membrane presequence translocase complex
biological process gene ontology GO:0006886 intracellular protein transport
Experimental evidence that interaction occurs intact EBI-9212082
additional information pubmed 16911507
evidence ontology ECO:0000353
additional information pubmed 17263664
Curated by: IntAct