title: Tim50, a novel component of the TIM23 preprotein translocase of mitochondria.
abstract: The preprotein translocase of the inner membrane of mitochondria (TIM23 complex) is the main entry gate for proteins of the matrix and the inner membrane. We isolated the TIM23 complex of Neurospora crassa. Besides Tim23 and Tim17, it contained a novel component, referred to as Tim50. Tim50 spans the inner membrane with a single transmembrane segment and exposes a large hydrophilic domain in the intermembrane space. Tim50 is essential for viability of yeast. Mitochondria from cells depleted of Tim50 displayed strongly reduced import kinetics of preproteins using the TIM23 complex. Tim50 could be cross-linked to preproteins that were halted at the level of the translocase of the outer membrane (TOM complex) or spanning both TOM and TIM23 complexes. We suggest that Tim50 plays a crucial role in the transfer of preproteins from the TOM complex to the TIM23 complex through the intermembrane space.
authors.affiliation: Adolf-Butenandt-Institut, Lehrstuhl für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, D-81377 München, Germany.
authors.forename: Dejana
authors.initials: D
authors.lastname: Mokranjac
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Paschen
authors.forename: Christian
authors.initials: C
authors.lastname: Kozany
authors.forename: Holger
authors.initials: H
authors.lastname: Prokisch
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: Hoppins
authors.forename: Frank E
authors.initials: FE
authors.lastname: Nargang
authors.forename: Walter
authors.initials: W
authors.lastname: Neupert
authors.forename: Kai
authors.initials: K
authors.lastname: Hell
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D003576:Electron Transport Complex IV; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D009491:Neurospora / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000302:isolation & purification / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; C090858:OXA1 protein; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae; C469615:TIM50 protein, S cerevisiae; D003576:Electron Transport Complex IV