内质网蛋白57与蛋白二硫键异构酶和钙网蛋白竞争性结合。

ERp57 binds competitively to protein disulfide isomerase and calreticulin.

作者信息

Kimura Taiji, Imaishi Keisuke, Hagiwara Yasunari, Horibe Tomohisa, Hayano Toshiya, Takahashi Nobuhiro, Urade Reiko, Kato Koichi, Kikuchi Masakazu

机构信息

Department of Bioscience and Technology, Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan.

出版信息

Biochem Biophys Res Commun. 2005 May 27;331(1):224-30. doi: 10.1016/j.bbrc.2005.03.147.

DOI:10.1016/j.bbrc.2005.03.147

PMID:15845382

Abstract

In this study, we screened for protein disulfide isomerase (PDI)-binding proteins in bovine liver microsomes under strict salt concentrations, using affinity column chromatography. One main band observed using SDS-PAGE was identified as ERp57 (one of the PDI family proteins) by LC-MS/MS analysis. The K(D) value of PDI binding to ERp57 was calculated as 5.46x10(-6)M with the BIACORE system. The interactions between PDI and ERp57 occurred specifically at their a and b domains, respectively. Interestingly, low concentrations of ERp57 enhanced the chaperone activity of PDI, while high concentrations interfered with chaperone activity. On the other hand, ERp57 did not affect the isomerase activity of PDI. Additionally, following pre-incubation of ERp57 with calreticulin (CRT), decreased interactions were observed between ERp57 and PDI, and vice versa. Based on the data, we propose that once ERp57 binds to PDI or CRT, the resultant complex inhibits further interactions. Therefore, ERp57 selectively forms a protein-folding complex with PDI or CRT in ER.

摘要

在本研究中，我们使用亲和柱色谱法，在严格的盐浓度条件下，对牛肝微粒体中的蛋白质二硫键异构酶（PDI）结合蛋白进行了筛选。通过SDS-PAGE观察到的一条主要条带，经液相色谱-串联质谱（LC-MS/MS）分析鉴定为ERp57（PDI家族蛋白之一）。使用BIACORE系统计算得出PDI与ERp57的解离常数（K(D)）值为5.46×10⁻⁶M。PDI与ERp57之间的相互作用分别特异性地发生在它们的a和b结构域。有趣的是，低浓度的ERp57增强了PDI的伴侣活性，而高浓度则干扰了伴侣活性。另一方面，ERp57不影响PDI的异构酶活性。此外，在ERp57与钙网蛋白（CRT）预孵育后，观察到ERp57与PDI之间的相互作用减少，反之亦然。基于这些数据，我们提出一旦ERp57与PDI或CRT结合，形成的复合物会抑制进一步的相互作用。因此，ERp57在内质网中选择性地与PDI或CRT形成蛋白质折叠复合物。