title: Probing the membrane topology of a subunit of the mitochondrial protein translocase, Tim44, with biotin maleimide.
abstract: Tim44 is an essential component of the translocase of the inner mitochondrial membrane (TIM) complex that mediates transport of nuclear encoded mitochondrial precursors across the inner membrane. Here, we have investigated the topology of Tim44 by probing mitochondria with membrane impermeable 3-(N-maleimidopropionyl)biocytin (MPB) followed by the specific immunoprecipitation of modified proteins. Our data indicate that a single cysteine residue, Cys-369, located in the C-terminal domain of the yeast Tim44 is exposed to the mitochondrial intermembrane space.
authors.affiliation: Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 10691 Stockholm, Sweden. pavel@dbb.su.se
authors.forename: Pavel F
authors.initials: PF
authors.lastname: Pavlov
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Glaser
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001710:Biotin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000737:chemistry*; D007425:Intracellular Membranes / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology*; D008565:Membrane Proteins / Q000737:chemistry*; D008928:Mitochondria / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D021122:Protein Subunits; D021381:Protein Transport; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D008301:Maleimides; D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C077016:TIM44 protein, S cerevisiae; C489673:Timm44 protein, rat; C043592:maleimide; D001710:Biotin