Interaction of murine BiP/GRP78 with the DnaJ homologue MTJ1
Interaction of murine BiP/GRP78 with the DnaJ homologue MTJ1
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DOI：
10.1074/jbc.m001333200
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发表时间：
2000-06-30
影响因子：
4.8
通讯作者：
Blond, SY
中科院分区：
文献类型：
--
作者：
Chevalier, M;Rhee, H;Blond, SY
Hsp 70蛋白的活性受辅助蛋白的调节，其中研究最多的是DnaJ样蛋白家族的成员。BiP/GRP 78陪伴内质网中分泌蛋白和膜蛋白的移位和成熟。到目前为止，还没有DnaJ样伴侣被描述为调节哺乳动物BiP/GRP 78的功能。我们在这里显示，鼠BiP/GRP 78与鼠跨膜蛋白MTJ 1（J-MTJ 1）的内腔J结构域相互作用。J-MTJ 1在化学计量浓度下刺激BiP/GRP 78的ATP酶活性。BiP/GRP 78的C-末端尾部对于与J-MTJ 1的相互作用不是必需的，使得分子的这一部分的功能仍然不清楚。J-MTJ 1和BiP/GRP 78之间的物理相互作用是稳定的，并且可以通过所有DnaJ样蛋白质共享的高度保守的HPD基序中的单个组氨酸->谷氨酰胺取代来消除。J-MTJ 1片段，而不是突变体J-MTJ 1：H89 Q片段，刺激大肠杆菌DnaK的ATP酶活性，尽管浓度高于其真正的伴侣DnaJ。全长DnaJ在研究的浓度范围内不刺激BiP。这些结果表明，MTJ 1的J结构域足以与BiP/GRP 78相互作用，并且不能被E. coli DnaJ.
The activity of Hsp70 proteins is regulated by accessory proteins, among which the most studied are the members of the DnaJ-like protein family. BiP/GRP78 chaperones the translocation and maturation of secreted and membrane proteins in the endoplasmic reticulum. No DnaJ-like partner has been described so far to regulate the function of mammalian BiP/GRP78. We show here that murine BiP/GRP78 interacts with the lumenal J domain of the murine transmembrane protein MTJ1 (J-MTJ1). J-MTJ1 stimulates the ATPase activity of BiP/GRP78 at stoichiometric concentrations. The C-terminal tail of BiP/GRP78 is not required for the interaction with J-MTJ1, leaving the function of this portion of the molecule still unclear. Physical interactions between J-MTJ1 and BiP/GRP78 are stable and can be abolished by a single histidine --> glutamine substitution in the highly conserved HPD motif shared by all DnaJ-like proteins. The J-MTJ1 fragment, but not the mutant J-MTJ1:H89Q fragment, stimulates the ATPase activity of Escherichia coli DnaK, although at a higher concentration than its genuine partner DnaJ. Full-length DnaJ does not stimulate BiP over the range of concentrations investigated. These results indicate that the J domain of MTJ1 is sufficient for its interaction with BiP/GRP78 and cannot be substituted by E. coli DnaJ.