Hsp70 proteins, similar to Escherichia coli DnaK, in chloroplasts and mitochondria of Euglena gracilis

Dekel Amir-Shapira, Thomas Leustek, Barbara Dalie, Herbert Weissbach, Nathan Brot

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

The heat-shock response of Euglena gracilis was studied by pulse-labeling cells with [35S]sulfate at both the normal growth temperature (21°C) and an elevated temperature (36°C). Analysis of the labeled proteins by polyacrylamide gel electrophoresis indicated that the rate of synthesis of at least 3 major and 15 minor polypeptides increased in cells grown at the higher temperature. Three of the proteins appear to be immunologically related to the ubiquitous ≈70-kDa heat-shock protein (Hsp70) family. One protein of 68 kDa was found in the cytoplasm (P68cyt) and was the major heat-shock protein in Euglena gracilis. Two other proteins, 68 and 70 kDa, were localized in mitochondria (P68mit) and chloroplasts (P70chl), respectively, and they crossreacted with a polyclonal antibody raised against the Escherichia coli heat-shock protein DnaK. Like DnaK, P68mit and P70chl could be phosphorylated in vitro with [γ-32P]ATP in a reaction that was stimulated by Ca2+. A protein with characteristics similar to those of P70chl was also found in chloroplasts isolated from maize and spinach.

Original languageAmerican English
Pages (from-to)1749-1752
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number5
StatePublished - Mar 1990
Externally publishedYes

ASJC Scopus subject areas

  • General

Keywords

  • Heat-shock proteins
  • Organelles
  • Phosphorylation

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