title: A constitutive form of heat-shock protein 70 is located in the outer membranes of mitochondria from rat liver.
abstract: HSP73, the constitutive form of heat-shock protein 70, has been implicated in the translocation of preproteins across the mitochondrial membranes, being required for maintaining mitochondrial preproteins in an import competent conformation. Here we report that highly purified mitochondrial outer membranes contain a protein indistinguishable from HSP73 as a tightly associated peripheral component of the membrane. This membrane form of HSP73 was photolabelled with [alpha-32P]ATP and could be released from the outer membrane with sodium carbonate, but not after incubation of the membranes with salt or with ATP. A sensitive immunoassay with an anti-HSP73 monoclonal antibody, revealed the association of HSP73 with mitochondrial outer membrane vesicles at a level similar to that of preprotein import receptors.
authors.affiliation: Department of Biochemistry, La Trobe University, Bundoora, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Lithgow
authors.forename: M
authors.initials: M
authors.lastname: Ryan
authors.forename: R L
authors.initials: RL
authors.lastname: Anderson
authors.forename: P B
authors.initials: PB
authors.lastname: Høj
authors.forename: N J
authors.initials: NJ
authors.lastname: Hoogenraad
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006360:Heat-Shock Proteins / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000737:chemistry* / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008930:Mitochondria, Liver / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D051381:Rats; D013367:Submitochondrial Particles / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D000255:Adenosine Triphosphate