Stch encodes the ‘ATPase core’ of a microsomal stress 70 protein.
Stch encodes the ‘ATPase core’ of a microsomal stress 70 protein.
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DOI：
10.1002/j.1460-2075.1994.tb06371.x
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发表时间：
1994-03
期刊：
影响因子：
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通讯作者：
G. Otterson;G. C. Flynn;R. Kratzke;R. Kratzke;A. Coxon;P. Johnston;F. Kaye;F. Kaye
中科院分区：
文献类型：
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作者：
G. Otterson;G. C. Flynn;R. Kratzke;R. Kratzke;A. Coxon;P. Johnston;F. Kaye;F. Kaye
Stress70 蛋白伴侣家族在胞浆蛋白和分泌蛋白的加工中发挥着核心作用。我们克隆了一种人类 cDNA，命名为 Stch，它在大鼠组织中保守，编码应激 70 蛋白伴侣家族的一个新的微粒体相关成员。 Stch mRNA 在所有人类细胞类型中组成型表达，并通过与钙离子载体 A23187 一起孵育来诱导，但不能通过暴露于热休克来诱导。对预测的氨基酸序列的检查表明，STCH 产物包含独特的疏水前导序列，并在stress70基因家族的氨基末端结构域内具有同源性，但在 ATP 结合结构域内插入了 50 个残基，并截短了羧基末端肽结合区域。免疫荧光和亚细胞分析表明，STCH 主要以 60 kDa 的形式迁移，并富含膜结合的微粒体部分。然而，与纯化的 BiP 和 dnaK 相比，STCH 表现出独立于肽刺激的 ATP 酶活性。因此，Stch 编码钙诱导的微粒体相关 ATP 酶活性，其特性类似于蛋白水解切割的 N 端 HSC70/BiP 片段。这种截短的stress70分子可能会增加细胞对蛋白质加工要求的反应的多样性。
The stress70 protein chaperone family plays a central role in the processing of cytosolic and secretory proteins. We have cloned a human cDNA, designated Stch, that is conserved in rat tissues and which encodes a novel microsome‐associated member of the stress70 protein chaperone family. Stch mRNA is constitutively expressed in all human cell types and is induced by incubation with the calcium ionophore A23187, but not by exposure to heat shock. Inspection of the predicted amino acid sequence reveals that the STCH product contains a unique hydrophobic leader sequence and shares homology within the amino terminal domains of the stress70 gene family, but has a 50 residue insertion within the ATP‐binding domains and truncates the carboxyl terminal peptide‐binding region. Immunofluorescent and subcellular analyses show that STCH migrates predominantly as a 60 kDa species and is enriched in a membrane‐bound microsome fraction. In contrast to purified BiP and dnaK, however, STCH demonstrates ATPase activity that is independent of peptide stimulation. Stch, therefore, encodes a calcium‐inducible, microsome‐associated ATPase activity with properties similar to a proteolytically cleaved N‐terminal HSC70/BiP fragment. This truncated stress70 molecule may allow increased diversity in cellular responses to protein processing requirements.