Amir-Shapira D, Leustek T, Dalie B, Weissbach H, Brot N
Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.
Proc Natl Acad Sci U S A. 1990 Mar;87(5):1749-52. doi: 10.1073/pnas.87.5.1749.
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.
通过在正常生长温度（21摄氏度）和升高温度（36摄氏度）下用[35S]硫酸盐对纤细裸藻细胞进行脉冲标记，研究了其热休克反应。通过聚丙烯酰胺凝胶电泳对标记蛋白质进行分析表明，在较高温度下生长的细胞中，至少3种主要多肽和15种次要多肽的合成速率增加。其中三种蛋白质似乎与普遍存在的约70 kDa热休克蛋白（Hsp70）家族存在免疫相关性。在细胞质中发现了一种68 kDa的蛋白质（P68cyt），它是纤细裸藻中的主要热休克蛋白。另外两种蛋白质，68 kDa和70 kDa，分别定位于线粒体（P68mit）和叶绿体（P70chl）中，并且它们与针对大肠杆菌热休克蛋白DnaK产生的多克隆抗体发生交叉反应。与DnaK一样，P68mit和P70chl在体外可以用[γ-32P]ATP进行磷酸化，该反应受到Ca2+的刺激。在从玉米和菠菜中分离出的叶绿体中也发现了一种具有与P70chl相似特征的蛋白质。
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