Hsp105 but not Hsp70 family proteins suppress the aggregation of heat-denatured protein in the presence of ADP |
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Authors: | Yamagishi Nobuyuki Ishihara Keiichi Saito Youhei Hatayama Takumi |
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Institution: | Department of Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan. |
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Abstract: | Hsp105alpha and Hsp105beta are mammalian members of the Hsp105/110 family, a diverged subgroup of the Hsp70 family. Here, we show that Hsp105alpha and Hsp105beta bind non-native protein through the beta-sheet domain and suppress the aggregation of heat-denatured protein in the presence of ADP rather than ATP. In contrast, Hsc70/Hsp40 suppressed the aggregation of heat-denatured protein in the presence of ATP rather than ADP. Furthermore, the overexpression of Hsp105alpha but not Hsp70 in COS-7 cells rescued the inactivation of luciferase caused by ATP depletion. Thus, Hsp105/110 family proteins are suggested to function as a substitute for Hsp70 family proteins to suppress the aggregation of denatured proteins in cells under severe stress, in which the cellular ATP level decreases markedly. |
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Keywords: | Hsp105α Hsp105β Hsc70 Thermal aggregation ATP ADP |
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