title: Characterization of the insertase for β-barrel proteins of the outer mitochondrial membrane.
abstract: The TOB-SAM complex is an essential component of the mitochondrial outer membrane that mediates the insertion of β-barrel precursor proteins into the membrane. We report here its isolation and determine its size, composition, and structural organization. The complex from Neurospora crassa was composed of Tob55-Sam50, Tob38-Sam35, and Tob37-Sam37 in a stoichiometry of 1:1:1 and had a molecular mass of 140 kD. A very minor fraction of the purified complex was associated with one Mdm10 protein. Using molecular homology modeling for Tob55 and cryoelectron microscopy reconstructions of the TOB complex, we present a model of the TOB-SAM complex that integrates biochemical and structural data. We discuss our results and the structural model in the context of a possible mechanism of the TOB insertase.
authors.affiliation: Max-Planck Institut für Biochemie, Abteilung für zelluläre Biochemie, D-82152 Martinsried, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Klein
authors.forename: Lars
authors.initials: L
authors.lastname: Israel
authors.forename: Sebastian W K
authors.initials: SW
authors.lastname: Lackey
authors.forename: Frank E
authors.initials: FE
authors.lastname: Nargang
authors.forename: Axel
authors.initials: A
authors.lastname: Imhof
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
authors.forename: Walter
authors.initials: W
authors.lastname: Neupert
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Thomas
mesh_terms: D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D008958:Models, Molecular; D009492:Neurospora crassa / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D008565:Membrane Proteins