Identifying and characterizing a structural domain of protein disulfide isomerase
Identifying and characterizing a structural domain of protein disulfide isomerase
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DOI：
10.1021/bi960763s
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发表时间：
1996-08-13
期刊：
影响因子：
2.9
通讯作者：
Creighton, TE
中科院分区：
文献类型：
--
作者：
Darby, NJ;Kemmink, J;Creighton, TE
蛋白质二硫键异构酶（PDI）是一种多结构域蛋白质，但其结构域的数目和性质尚不清楚。两个结构域，a和a '，这是同源的硫氧还蛋白和催化二硫键形成的活性，已被确定和表征。已经表达了PDI序列的N-末端一半的部分，并且通过有限的蛋白水解描绘了其折叠结构的限制。除了a-结构域之外，还鉴定了对巯基/二硫基没有活性的结构域的边界，命名为B。该结构域已独立产生;其合作展开过渡及其CD和NMR光谱证实，它是一个独立的折叠结构，当PDI的一部分。b结构域与a结构域的融合，如在PDI的前半部分中自然发生的。基本上不改变α-结构域的催化活性。它仍然仅催化完整PDI的硫醇/二硫键交换反应的子集，并且催化蛋白质二硫键重排的能力降低。a-和b-结构域在结构上占PDI多肽链的几乎所有前半部分，并且不太可能存在与雌激素受体同源的第三个结构域。b-结构域与钙螯合蛋白（一种来自肌肉肌浆网的钙结合蛋白）具有一定的序列同源性。
Protein disulfide isomerase (PDI) appears on the basis of its primary structure to be a multidomain protein, but the number and nature of the domains has been uncertain. Two of the domains, a and a', which are homologous to thioredoxin and active in catalysis of disulfide bond formation, have been identified and characterized previously. Sections of the N-terminal half of the PDI sequence have been expressed and the limits of their folded structures delineated by limited proteolysis. In addition to the a-domain, the boundaries of a domain with no activity on thiol/disulfide groups, designated b, have been identified. This domain has been produced independently; its cooperative unfolding transition and its CD and NMR spectra confirm that it is an autonomously folded structure in isolation and when part of PDI. Fusion of the b-domain to the a-domain, as occurs naturally in the first half of PDI. did not alter substantially the catalytic activity of the a-domain. It still catalyzes only a subset of the thiol/disulfide exchange reactions of intact PDI and has a reduced ability to catalyze protein disulfide rearrangements. The a- and b-domains account structurally for virtually all of the first half of the PDI polypeptide chain, and it is very unlikely that there exists a proposed third domain homologous to the estrogen receptor. The b-domain exhibits some sequence homology to calsequestrin, a calcium binding protein from the sarcoplasmic reticulum of muscle.