Cooperation of TOM and TIM23 complexes during translocation of proteins into mitochondria

Karin Waegemann, Dušan Popov-Čeleketić, Walter Neupert, Abdussalam Azem, Dejana Mokranjac*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Translocation of the majority of mitochondrial proteins from the cytosol into mitochondria requires the cooperation of TOM and TIM23 complexes in the outer and inner mitochondrial membranes. The molecular mechanisms underlying this cooperation remain largely unknown. Here, we present biochemical and genetic evidence that at least two contacts from the side of the TIM23 complex play an important role in TOM-TIM23 cooperation in vivo. Tim50, likely through its very C-terminal segment, interacts with Tom22. This interaction is stimulated by translocating proteins and is independent of any other TOM-TIM23 contact known so far. Furthermore, the exposure of Tim23 on the mitochondrial surface depends not only on its interaction with Tim50 but also on the dynamics of the TOM complex. Destabilization of the individual contacts reduces the efficiency of import of proteins into mitochondria and destabilization of both contacts simultaneously is not tolerated by yeast cells. We conclude that an intricate and coordinated network of protein-protein interactions involving primarily Tim50 and also Tim23 is required for efficient translocation of proteins across both mitochondrial membranes.

Original languageEnglish
Pages (from-to)1075-1084
Number of pages10
JournalJournal of Molecular Biology
Issue number5
StatePublished - 13 Mar 2015


FundersFunder number
Deutsche Forschungsgemeinschaft
German-Israeli Foundation for Scientific Research and Development


    • TIM23
    • mitochondria
    • protein sorting
    • protein translocation


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