期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：5
页码：1749-1752
DOI：10.1073/pnas.87.5.1749
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The heat-shock response of Euglena gracilis was studied by pulse-labeling cells with [35S]sulfate at both the normal growth temperature (21 degrees C) and an elevated temperature (36 degrees 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 approximately 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 [gamma-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.
