title: The mitochondrial receptor complex: the small subunit Mom8b/Isp6 supports association of receptors with the general insertion pore and transfer of preproteins.
abstract: The mitochondrial outer membrane contains import receptors for preproteins and a multisubunit general insertion pore. Several small outer membrane proteins (< 10 kDa) have been identified by their association with receptors or the general insertion pore, yet little is known about their function. Here, we present evidence that the biochemically identified Mom8b and the genetically identified Isp6 are identical. A deletion of Mom8b/Isp6 in Saccharomyces cerevisiae leads to (i) a delay of import of preproteins, (ii) stabilization of preprotein binding to receptors and the general insertion pore, and (iii) destabilization of the interaction between receptors and the general insertion pore. These results suggest that Mom8b supports the cooperativity between receptors and the general insertion pore and facilitates the release of preproteins from import components and thereby promotes efficient transfer of preproteins.
authors.affiliation: Biochemisches Institut, Universität Freiburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Alconada
authors.forename: M
authors.initials: M
authors.lastname: Kübrich
authors.forename: M
authors.initials: M
authors.lastname: Moczko
authors.forename: A
authors.initials: A
authors.lastname: Hönlinger
authors.forename: N
authors.initials: N
authors.lastname: Pfanner
mesh_terms: D001692:Biological Transport; D002451:Cell Compartmentation; D005656:Fungal Proteins / Q000378:metabolism*; D017353:Gene Deletion; D007425:Intracellular Membranes / Q000737:chemistry; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000737:chemistry*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011499:Protein Processing, Post-Translational; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; C082532:TOM6 protein, S cerevisiae