title: Identification of Tam41 maintaining integrity of the TIM23 protein translocator complex in mitochondria.
abstract: Newly synthesized mitochondrial proteins are imported into mitochondria with the aid of protein translocator complexes in the outer and inner mitochondrial membranes. We report the identification of yeast Tam41, a new member of mitochondrial protein translocator systems. Tam41 is a peripheral inner mitochondrial membrane protein facing the matrix. Disruption of the TAM41 gene led to temperature-sensitive growth of yeast cells and resulted in defects in protein import via the TIM23 translocator complex at elevated temperature both in vivo and in vitro. Although Tam41 is not a constituent of the TIM23 complex, depletion of Tam41 led to a decreased molecular size of the TIM23 complex and partial aggregation of Pam18 and -16. Import of Pam16 into mitochondria without Tam41 was retarded, and the imported Pam16 formed aggregates in vitro. These results suggest that Tam41 facilitates mitochondrial protein import by maintaining the functional integrity of the TIM23 protein translocator complex from the matrix side of the inner membrane.
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Tamura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Harada
authors.forename: Koji
authors.initials: K
authors.lastname: Yamano
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Watanabe
authors.forename: Daigo
authors.initials: D
authors.lastname: Ishikawa
authors.forename: Chié
authors.initials: C
authors.lastname: Ohshima
authors.forename: Shuh-ichi
authors.initials: S
authors.lastname: Nishikawa
authors.forename: Hayashi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
mesh_terms: D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D013696:Temperature; D013997:Time Factors; D015003:Yeasts / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D033681:Mitochondrial Membrane Transport Proteins; D020409:Molecular Motor Proteins; D021122:Protein Subunits