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  • Modular structure of the TIM23 preprotein translocase of mitochondria
    Milisav, Irina ...
    The TIM23 complex mediates import into mitochondria of nuclear encoded preproteins with a matrix-targeting signal. It is composed of the integral membrane proteins Tim17 and Tim23 and the peripheral ... membrane protein Tim44, which recruits mitochondrial Hsp70 to the sites of protein import. We have analyzed the functions of these constituents using a combined genetic and biochemical approach. Depletion of either Tim17 or Tim23 led to loss of importcompetence of mitochondria and to a reduction in the number of preprotein-conducting channels. Upon depletion of Tim44, mitochondria also lost their ability to import proteins but maintained normal numbers of import channels. In the absence of Tim44 precursor protein was specifically recognized. The presequence was translocated in a dependent manner across the inner membrane and cleaved by matrix-processing peptidase. However, the preprotein did not move further into the matrix but rather underwent retrograde sliding out of the TIM23 complex. Thus, the TIM23 complex is composed of functionally independent modules. Tim17 and Tim23 are necessary for initiating translocation, whereas Tim44 and mitochondrial Hsp70 are indispensable for complete transport of preproteins and for unfolding of folded domains of preproteins.
    Vir: The Journal of biological chemistry. - ISSN 0021-9258 (Letn. 276, št. 28, July 2001, str. 25856-25861)
    Vrsta gradiva - članek, sestavni del
    Leto - 2001
    Jezik - angleški
    COBISS.SI-ID - 13912537

vir: The Journal of biological chemistry. - ISSN 0021-9258 (Letn. 276, št. 28, July 2001, str. 25856-25861)
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