title: hTom34: a novel translocase for the import of proteins into human mitochondria.
abstract: Most mitochondrial proteins are nuclear encoded, synthesized on cytosolic ribosomes, and imported into the mitochondria. We have identified and characterized a 309 amino acid human protein with a molecular weight of 34 kDa that functions as a subunit of the translocase for the import of such proteins. hTom34 (34-kDa Translocase of the Outer Mitochondrial Membrane) is displayed on the surface of mitochondria and is resistant to extraction under alkaline conditions. Antibodies raised against hTom34 specifically inhibit in vitro import of the mitochondrial precursor protein preornithine transcarbamylase into mitochondria isolated from rat liver. Based on trypsin digestion experiments, the receptor has a large (27 kDa) C-terminal domain exposed to the cytosol. This novel component of the protein import machinery possesses a 62 residue motif conserved with the Tom70 family of mitochondrial receptors but otherwise appears to have no counterpart so far characterized in the mitochondria of any other species.
authors.affiliation: School of Biochemistry, La Trobe University, Bundoora, Victoria, Australia.
authors.forename: S D
authors.initials: SD
authors.lastname: Nuttall
authors.forename: B J
authors.initials: BJ
authors.lastname: Hanson
authors.forename: M
authors.initials: M
authors.lastname: Mori
authors.forename: N J
authors.initials: NJ
authors.lastname: Hoogenraad
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry; D051381:Rats; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D004792:Enzyme Precursors; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010446:Peptide Fragments; C108485:TOMM34 protein, human; C052289:preornithine carbamoyltransferase; D009954:Ornithine Carbamoyltransferase