title: Tim23-Tim50 pair coordinates functions of translocators and motor proteins in mitochondrial protein import.
abstract: Mitochondrial protein traffic requires coordinated operation of protein translocator complexes in the mitochondrial membrane. The TIM23 complex translocates and inserts proteins into the mitochondrial inner membrane. Here we analyze the intermembrane space (IMS) domains of Tim23 and Tim50, which are essential subunits of the TIM23 complex, in these functions. We find that interactions of Tim23 and Tim50 in the IMS facilitate transfer of precursor proteins from the TOM40 complex, a general protein translocator in the outer membrane, to the TIM23 complex. Tim23-Tim50 interactions also facilitate a late step of protein translocation across the inner membrane by promoting motor functions of mitochondrial Hsp70 in the matrix. Therefore, the Tim23-Tim50 pair coordinates the actions of the TOM40 and TIM23 complexes together with motor proteins for mitochondrial protein import.
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Tamura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Harada
authors.forename: Takuya
authors.initials: T
authors.lastname: Shiota
authors.forename: Koji
authors.initials: K
authors.lastname: Yamano
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Watanabe
authors.forename: Mihoko
authors.initials: M
authors.lastname: Yokota
authors.forename: Hayashi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Hiromi
authors.initials: H
authors.lastname: Sesaki
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
mesh_terms: D049109:Cell Proliferation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051336:Mitochondrial Membranes / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D025941:Protein Interaction Mapping; D021382:Protein Sorting Signals; D021381:Protein Transport / Q000502:physiology; D015003:Yeasts / Q000166:cytology / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D020409:Molecular Motor Proteins; D021382:Protein Sorting Signals