Cited by 271Heat shock proteins researchUbiquitin and proteasome pathwaysMitochondrial Function and Pathology

Immunoelectron Microscopic Localization of the 60-kDa Heat Shock Chaperonin Protein (Hsp60) in Mammalian Cells

Soltys, Bohdan J., Gupta, Radhey S.·1996·Experimental Cell Research

Abstract

The subcellular distribution of the 60-kDa heat shock protein (Hsp60) was examined in a variety of mammalian cells and tissues, including Chinese hamster ovary cells, human fibroblasts, B-SC-1 kidney cells, Daudi Burkitt's lymphoma cells, and rat liver, by immunogold electron microscopy employing six different monoclonal and polyclonal antibodies that are specific for Hsp60. In cryosections or LR Gold sections of different cultured cells, intense labeling of mitochondria was obtained, typically 200-500 gold particles per mitochondrion and accounting for 80-85% of the total gold particles. In addition, however, in all cell types and using all of the antibodies, about 15-20% of the labeling due to Hsp60 was seen at discrete extramitochondrial sites. Such sites included those in close proximity to mitochondrial outer membranes, foci on endoplasmic reticulum, on the cell surface, and in unidentified vesicles. In cryosections of rat liver, specific labeling due to Hsp60 antibodies was also observed within peroxisomes. Labeling of all cellular components by these antibodies could be prevented by preadsorption with purified recombinant mitochondrial Hsp60 indicating that the labeling is specific for Hsp60. Biotin labeling of cell surface proteins results in biotinylation of Hsp60 as analyzed by immunoprecipitation and Western blots, providing further evidence for Hsp60 presence on the plasma membrane. Immunoprecipitation experiments with Hsp60 antibodies show that under normal conditions no detectable precursor Hsp60 protein is present in cells. However, in cells treated with the potassium ionophore nonactin, which blocks mitochondrial import, only the precursor form of Hsp60 accumulates, providing evidence that at least partial mitochondrial import of Hsp60 is necessary for its maturation. These results also provide evidence that no other 60-kDa protein other than mitochondrial Hsp60 is recognized by the antibodies used for electron microscopy. These findings raise interesting questions concerning the possible role of Hsp60 at extramitochondrial sites.

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Crossref · 10.1006/excr.1996.0003

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Authors
Soltys, B. J., & Gupta, R. S.
Affiliations
McMaster University (CA)
Venue
Experimental Cell Research
Publisher
Elsevier BV
Published
1996-01
Volume
222
Issue
1
Pages
16-27
ISSN
0014-4827 (ISSN-L)
OpenAlex
W2063171792
Cited by
271
References
0
Citations by year
2026: 3 · 2025: 4 · 2024: 5 · 2023: 2 · 2022: 5 · 2021: 5 · 2020: 8 · 2019: 11 · 2018: 8 · 2017: 8 · 2016: 4 · 2015: 5 · 2014: 8 · 2013: 8 · 2012: 10
FWCI
4.80
Type
journal article
Language
en
Open access
closed
Locations
  • Experimental Cell Research (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Heat shock proteins research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ubiquitin and proteasome pathways
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Mitochondrial Function and Pathology
Keywords
HSP60, 60 kDa heat shock protein, subcellular localization, mitochondrial Hsp60, mitochondrial protein import, nonactin, plasma membrane, peroxisomes, endoplasmic reticulum, immunogold electron microscopy, rat liver, Burkitt's lymphoma cells, fibroblasts
MeSH terms
Animals, Antibody Specificity, Cell Membrane, Cells, Cultured, Cytoplasm, Cytoplasmic Granules, Endoplasmic Reticulum, Cricetinae, Humans, Ionophores, Liver, Mammals, Microbodies, Mitochondria, Protein Precursors, Organelles, Microscopy, Immunoelectron, CHO Cells, Chaperonin 60, Macrolides, Rats

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