Clusterin has chaperone-like activity similar to that of small heat shock proteins
Clusterin has chaperone-like activity similar to that of small heat shock proteins
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DOI：
10.1074/jbc.274.11.6875
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发表时间：
1999-03-12
影响因子：
4.8
通讯作者：
Wilson, MR
中科院分区：
文献类型：
--
作者：
Humphreys, DT;Carver, JA;Wilson, MR
聚簇蛋白是一种高度保守的蛋白质，在多种应激条件下，许多细胞类型的表达水平增加。聚簇素的真正生理功能尚未确定。本文的研究结果首次证明了簇蛋白具有类似伴侣蛋白的活性。在生理浓度下，聚簇蛋白有效地保护谷胱甘肽s -转移酶和过氧化氢酶免受热诱导沉淀，α -乳白蛋白和牛血清白蛋白免受二硫苏糖醇还原诱导的沉淀。酶联免疫吸附试验数据显示，聚簇蛋白优先结合热应激谷胱甘肽s -转移酶和二硫苏糖处理的牛血清白蛋白和α -乳白蛋白。粒径排除层析和sds -聚丙烯酰胺凝胶电泳分析表明，聚簇蛋白与所有被测蛋白形成高分子量复合物（HMW）。小热休克蛋白（sHSP）也以这种方式起作用，防止蛋白质沉淀，保护细胞免受热量和其他压力。在HMW复合物形成过程中，聚簇蛋白与应激蛋白的化学计量亚单位摩尔比（测试的四种蛋白质的亚单位摩尔比范围为1.0:1.3至1.0:11）小于报道的shsp介导的HMW复合物形成的比率（1.0:1.0或更高），表明聚簇蛋白是一种非常有效的伴侣蛋白。我们的研究结果表明，聚簇蛋白可能在细胞保护中发挥类似shsp的作用。
Clusterin is a highly conserved protein which is expressed at increased levels by many cell types in response to a broad variety of stress conditions. A genuine physiological function for clusterin has not yet been established. The results presented here demonstrate for the first time that clusterin has chaperone-like activity. At physiological concentrations, clusterin potently protected glutathione S-transferase and catalase from heat-induced precipitation and alpha-lactalbumin and bovine serum albumin from precipitation induced by reduction with dithiothreitol. Enzyme-linked immunosorbent assay data showed that clusterin bound preferentially to heat-stressed glutathione S-transferase and to dithiothreitol-treated bovine serum albumin and alpha-lactalbumin. Size exclusion chromatography and SDS-polyacrylamide gel electrophoresis analyses showed that clusterin formed high molecular weight complexes (HMW) with all four proteins tested. Small heat shock proteins (sHSP) also act in this way to prevent protein precipitation and protect cells from heat and other stresses. The stoichiometric subunit molar ratios of clusterin:stressed protein during formation of HMW complexes (which for the four proteins tested ranged from 1.0:1.3 to 1.0:11) is less than the reported ratios for sHSP-mediated formation of HMW complexes (1.0:1.0 or greater), indicating that clusterin is a very efficient chaperone. Our results suggest that clusterin may play a sHSP-like role in cytoprotection.