Honda K, Hatayama T, Yukioka M
Department of Biochemistry, Osaka City University Medical School.
J Biochem. 1988 Jan;103(1):81-5. doi: 10.1093/oxfordjournals.jbchem.a122244.
HeLa cells synthesize a particular heat shock protein that is induced only by heat shock at 42 degrees C, and not at 45 degrees C or by other stresses that induce major heat shock proteins (Hatayama et al. (1986) Biochem. Biophys. Res. Commun. 137, 957-963). We further characterized the 42 degrees C-specific protein. This protein was induced in mouse FM 3A cells as well as in human HeLa cells. In both cell lines, the protein was resolved into two spots, a basic polypeptide and an acidc one. The mRNA of the protein was induced during the incubation of these cells at 42 degrees C, and the in vitro translation product of mRNA corresponded to the basic, not to the acidic, polypeptide. During the chase period for cells that were labeled with [35S]-methionine, the basic polypeptide of the protein decreased, and the acidic one increased, indicating that the protein was synthesized as the basic polypeptide and then somehow modified to become the acidic one. The 42 degrees C-specific protein was found only in the cytosol fraction, and not in the nuclear or other particulate fractions, in both HeLa and FM 3A cells. The results suggested that the 42 degrees C-specific protein may have some function in the cytoplasm of mammalian cells during mild heat shock.
海拉细胞合成一种特定的热休克蛋白，该蛋白仅在42摄氏度的热休克诱导下产生，在45摄氏度时不会产生，也不会由诱导主要热休克蛋白的其他应激因素诱导产生（畠山等人，（1986年）《生物化学与生物物理学研究通讯》137卷，957 - 963页）。我们进一步对这种42摄氏度特异性蛋白进行了表征。这种蛋白在小鼠FM 3A细胞以及人类海拉细胞中均被诱导产生。在这两种细胞系中，该蛋白可分离为两个斑点，一个是碱性多肽，另一个是酸性多肽。在这些细胞于42摄氏度孵育期间，该蛋白的mRNA被诱导产生，且mRNA的体外翻译产物对应于碱性多肽，而非酸性多肽。在用[35S] - 甲硫氨酸标记的细胞的追踪期内，该蛋白的碱性多肽减少，而酸性多肽增加，这表明该蛋白最初以碱性多肽形式合成，然后以某种方式被修饰成为酸性多肽。在海拉细胞和FM 3A细胞中，42摄氏度特异性蛋白仅存在于胞质溶胶组分中，而不存在于细胞核或其他颗粒组分中。结果表明，42摄氏度特异性蛋白可能在哺乳动物细胞轻度热休克期间的细胞质中发挥某种功能。
