TAP associates with a unique class I conformation, whereas calnexin associates with multiple class I forms in mouse and man.
TAP associates with a unique class I conformation, whereas calnexin associates with multiple class I forms in mouse and man.
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DOI：
10.4049/jimmunol.155.10.4726
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发表时间：
1995-11
影响因子：
4.4
通讯作者：
Beatriz M. Carreno;J. Solheim;M. Harris;Iwona T. Stroynowski;Janet M. Connolly;Ted H. Hansen
中科院分区：
文献类型：
--
作者：
Beatriz M. Carreno;J. Solheim;M. Harris;Iwona T. Stroynowski;Janet M. Connolly;Ted H. Hansen
为了确定三聚体I类复合体从头组装的规则，我们使用人类和小鼠细胞系确定了与calnexin或TAP相关的I类折叠/组装中间体。为了更好地表征与TAP相关的I类H链结构，使用了区分开放（64-3-7+）和折叠（30-5-7+）Ld重(H)链的小鼠单抗。我们在这里报道，开放形式的Ld与TAP具有独特和特异性的关联，并且与肽结合相一致的I类H链的构象变化诱导TAP释放。嵌合Ld/Q10显示TAP结合，表明可溶性I类分子可以结合TAP。如前所述，发现β 2m是H链与TAP结合所必需的。有趣的是，在人类I类阴性细胞系LCL 721.221中，β 2m与TAP相关，这表明β 2m可以在I类H链之前与TAP结合。与结合特定I类构象的TAP相反，在小鼠和人类I类分子的多种形式中检测到钙连联蛋白。最重要的是，我们首次发现β 2m组装形式的人类和小鼠I类分子与钙连联蛋白相互作用。基于这些发现，我们提出了一类异源三聚体的序列组装及其与TAP和calnexin相互作用的模型。
To define the rules governing de novo assembly of the trimeric class I complex, we have identified the class I folding/assembly intermediates associated with calnexin or TAP, using both human and mouse cell lines. To better characterize the class I H chain structure associated with TAP, mouse mAb that distinguish open (64-3-7+) vs folded (30-5-7+) Ld heavy (H) chains were used. We report here that open forms of Ld are uniquely and specifically associated with TAP and that the conformational change in the class I H chain coincident with peptide binding induces TAP release. Chimeric Ld/Q10 displayed TAP association, demonstrating that soluble class I molecules can bind TAP. As previously reported, beta 2m was found to be required for H chain association with TAP. Interestingly, beta 2m was associated with TAP in the human class I-negative cell line LCL 721.221, suggesting that beta 2m can bind to TAP before class I H chain. In contrast to TAP, which binds a specific class I conformation, calnexin was detected in association with multiple forms of both mouse and human class I. Most significantly, we show for the first time that beta 2m-assembled forms of human as well as mouse class I molecules interact with calnexin. Based on these findings, we propose a model for the sequential assembly of class I heterotrimers and their respective interactions with TAP and calnexin.