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Mokranjac D, et al.  (2005) The import motor of the yeast mitochondrial TIM23 preprotein translocase contains two different J proteins, Tim14 and Mdj2. J Biol Chem 280(36):31608-14

Abstract: The import motor of the mitochondrial TIM23 complex drives translocation of presequence- containing preproteins across the mitochondrial inner membrane in an ATP-dependent manner. Tim44 is the central component of the motor. It recruits mtHsp70 which binds the incoming preproteins. The J protein Tim14 stimulates the ATPase activity of mtHsp70, and thereby enables efficient binding of mtHsp70 to preproteins. Tim16 is a J-like protein which forms a stable subcomplex with Tim14 and recruits it to the translocase. All but one subunits of the TIM23 translocase are essential for yeast cell viability. Yeast cells contain a close homologue of Tim14, Mdj2. In contrast to Tim14, its deletion leads to no obvious growth defect. In the present study we analyzed Mdj2 and compared it to Tim14. Mdj2 forms a complex with Tim16 and is recruited to the TIM23 translocase. It stimulates the ATPase activity of mtHsp70 to the same extent as Tim14 does. Mdj2 is expressed at a lower level compared to Tim14 and its complex with Tim16 is less stable. However, overexpressed Mdj2 fully restores growth of cells lacking Tim14. We conclude that Mdj2 is a functional J protein and a component of the mitochondrial import motor.

Status: Published

Type: Journal Article

PubMed ID: 16027163

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Mokranjac D Sichting M Popov-Celeketic DA berg A Hell K Neupert W Papers in SGD Colleagues in SGD PubMed Google Scholar

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