title: The mitochondrial protein import machinery has multiple connections to the respiratory chain.
abstract: The mitochondrial inner membrane harbors the complexes of the respiratory chain and protein translocases required for the import of mitochondrial precursor proteins. These complexes are functionally interdependent, as the import of respiratory chain precursor proteins across and into the inner membrane requires the membrane potential. Vice versa the membrane potential is generated by the proton pumping complexes of the respiratory chain. Besides this basic codependency four different systems for protein import, processing and assembly show further connections to the respiratory chain. The mitochondrial intermembrane space import and assembly machinery oxidizes cysteine residues within the imported precursor proteins and is able to donate the liberated electrons to the respiratory chain. The presequence translocase of the inner membrane physically interacts with the respiratory chain. The mitochondrial processing peptidase is homologous to respiratory chain subunits and the carrier translocase of the inner membrane even shares a subunit with the respiratory chain. In this review we will summarize the import of mitochondrial precursor proteins and highlight these special links between the mitochondrial protein import machinery and the respiratory chain. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, Freiburg, Germany.
authors.forename: Bogusz
authors.initials: B
authors.lastname: Kulawiak
authors.forename: Jan
authors.initials: J
authors.lastname: Höpker
authors.forename: Michael
authors.initials: M
authors.lastname: Gebert
authors.forename: Bernard
authors.initials: B
authors.lastname: Guiard
authors.forename: Nils
authors.initials: N
authors.lastname: Wiedemann
authors.forename: Natalia
authors.initials: N
authors.lastname: Gebert
mesh_terms: D004579:Electron Transport / Q000502:physiology; D042963:Electron Transport Complex II / Q000378:metabolism; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D008954:Models, Biological; D021381:Protein Transport / Q000502:physiology
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; C478189:respiratory complex II; D042963:Electron Transport Complex II