Anchoring of the 26S proteasome to the organellar membrane by FKBP38
Anchoring of the 26S proteasome to the organellar membrane by FKBP38
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DOI：
10.1111/j.1365-2443.2007.01086.x
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发表时间：
2007-06-01
期刊：
影响因子：
2.1
通讯作者：
Nakayama, Keiichi I.
中科院分区：
文献类型：
--
作者：
Nakagawa, Tadashi;Shirane, Michiko;Nakayama, Keiichi I.
FK506 结合蛋白 38 (FKBP38) 是亲免蛋白家族的成员，存在于线粒体外膜和内质网 (ER) 膜中。为了研究 FKBP38 的生理功能，我们通过 FKBP38 免疫沉淀物的液相色谱和质谱分析，对人类细胞中与其相互作用的蛋白质进行了全面的搜索。因此发现 26S 蛋白酶体的几乎所有亚基都与 FKBP38 相互作用。体内免疫共沉淀分析证实，FKBP38 确实通过其三个串联四肽重复序列 (TPR) 与 26S 蛋白酶体结合。体外结合测定还表明，FKBP38 直接与 19S 蛋白酶体的 S4 亚基相互作用。免疫荧光分析表明，FKBP38 和 26S 蛋白酶体的亚细胞分布在线粒体处部分重叠。与野生型小鼠制备的小鼠胚胎成纤维细胞相比，Fkbp38(-/-)小鼠制备的小鼠胚胎成纤维细胞膜组分中蛋白酶体的丰度和活性均显着降低。这些结果表明 FKBP38 的功能是将 26S 蛋白酶体锚定在细胞器膜上。
FK506-binding protein 38 (FKBP38) is a member of the immunophilin family that resides in the mitochondrial outer membrane and the endoplasmic reticulum (ER) membrane. To investigate the physiological function of FKBP38, we performed a comprehensive search for proteins with which it interacts in human cells by liquid chromatographic and mass spectrometric analysis of FKBP38 immunoprecipitates. Almost all subunits of the 26S proteasome were thus found to interact with FKBP38. In vivo co-immunoprecipitation analyses confirmed that FKBP38 indeed associates with the 26S proteasome via its three tandem tetratricopeptide repeats (TPRs). Binding assays in vitro also revealed that FKBP38 directly interacts with the S4 subunit of the 19S proteasome. Immunofluorescence analysis demonstrated that the subcellular distributions of FKBP38 and the 26S proteasome partially overlapped at mitochondria. Both the abundance and activity of the proteasome in a membrane fraction were markedly reduced for mouse embryonic fibroblasts prepared from Fkbp38(-/-) mice compared with those prepared from wild-type mice. These results suggest that FKBP38 functions to anchor the 26S proteasome at the organellar membrane.