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A constitutive form of heat‐shock protein 70 is located in the outer membranes of mitochondria from rat liver
Author(s) -
Lithgow Trevor,
Ryan Michael,
Anderson Robin L.,
Høj Peter B.,
Hoogenraad Nicholas J.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80649-f
Subject(s) - membrane , bacterial outer membrane , heat shock protein , mitochondrion , inner mitochondrial membrane , microbiology and biotechnology , vesicle , translocase of the inner membrane , chemistry , biochemistry , biology , mitochondrial membrane transport protein , escherichia coli , gene
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 [α‐ 32 P]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.