Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1987 Jan;6(1):55-61.
doi: 10.1002/j.1460-2075.1987.tb04718.x.

Effect of heat shock on protein degradation in mammalian cells: involvement of the ubiquitin system

H A Parag, B Raboy, R G Kulka

Effect of heat shock on protein degradation in mammalian cells: involvement of the ubiquitin system

H A Parag et al. EMBO J. 1987 Jan.

Abstract

Exposure of cultured rat hepatoma (HTC) cells to a 43 degrees C heat shock transiently accelerates the degradation of the long-lived fraction of cellular proteins. The rapid phase of proteolysis which lasts approximately 2 h after temperature step-up is followed by a slower phase of proteolysis. During the first 2 h after temperature step-up there is a wave of ubiquitin conjugation to cellular proteins which is accompanied by a fall in ubiquitin and ubiquitinated histone 2A (uH2A) levels. Upon continued incubation at 43 degrees C the levels of ubiquitin conjugates fall with a corresponding increase of ubiquitin and uH2A to initial levels. The burst of protein degradation and ubiquitin conjugation after temperature step-up is not affected by the inhibition of heat shock protein synthesis. Cells of the FM3A ts85 mutant, which have a thermolabile ubiquitin activating enzyme (E1), do not accelerate protein degradation in response to a 43 degrees C heat shock, whereas wild-type FM3A mouse cells do. This observation indicates that the ubiquitin system is involved in the degradation of heat-denatured proteins. Sequential temperature jump experiments show that the extent of proteolysis at temperatures up to 43 degrees C is related to the final temperature and not to the number of steps taken to attain it. Temperature step-up to 45 degrees C causes the inhibition of intracellular proteolysis. We propose the following explanation of the above observations. Heat shock causes the conformational change or denaturation of a subset of proteins stable at normal temperatures.(ABSTRACT TRUNCATED AT 250 WORDS)

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Cell. 1984 May;37(1):57-66 - PubMed
    1. J Biol Chem. 1983 Aug 25;258(16):9597-600 - PubMed
    1. Proc Natl Acad Sci U S A. 1975 Jul;72(7):2626-30 - PubMed
    1. Nature. 1970 Aug 15;227(5259):680-5 - PubMed
    1. Adv Protein Chem. 1982;35:1-104 - PubMed

Publication types