title: Internal targeting signal of the BCS1 protein: a novel mechanism of import into mitochondria.
abstract: The BCS1 protein is anchored in the mitochondrial inner membrane via a single transmembrane domain and has an N(out)-C(in) topology. Unlike the majority of nuclear encoded mitochondrial preproteins, the BCS1 protein does not contain an N-terminal targeting sequence. A positively charged segment of amino acids which is located immediately C-terminal to the transmembrane domain acts as an internal targeting signal. In order to function, we postulate that this sequence co-operates with the transmembrane domain to form a tight hairpin loop structure. This loop is translocated across the inner membrane via the MIM/mt-Hsp70 machinery in a membrane potential-dependent manner. This novel mechanism of import and sorting of the BCS1 protein is proposed to represent a more general mechanism used by a number of inner membrane proteins.
authors.affiliation: Institut für Physiologische Chemie der Universität München, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Fölsch
authors.forename: B
authors.initials: B
authors.lastname: Guiard
authors.forename: W
authors.initials: W
authors.lastname: Neupert
authors.forename: R A
authors.initials: RA
authors.lastname: Stuart
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000595:Amino Acid Sequence; D001483:Base Sequence; D001693:Biological Transport, Active; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008954:Models, Biological; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D015394:Molecular Structure; D021382:Protein Sorting Signals / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: C472685:BCS1 protein, S cerevisiae; D017931:DNA Primers; D004271:DNA, Fungal; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D000074183:ATPases Associated with Diverse Cellular Activities