Absolute conservation of residue 6 of immunoglobulin heavy chain variable regions of class IIA is required for correct folding
Absolute conservation of residue 6 of immunoglobulin heavy chain variable regions of class IIA is required for correct folding
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DOI：
10.1093/protein/11.12.1267
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发表时间：
1998-12-01
期刊：
影响因子：
--
通讯作者：
Hoogenboom, HR
中科院分区：
文献类型：
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作者：
de Haard, HJW;Kazemier, B;Hoogenboom, HR
在研究几种鼠源单克隆抗体的单链抗体（scFv）的表达时，我们发现重链可变区框架区1中的残基6在抗体折叠中起着至关重要的作用。当在该位置处温和型残基谷氨酰胺（Q）被谷氨酸（E）取代时，具有重链可变区（VH）亚组IIA的三种鼠抗体的结合活性完全丧失。可溶性scFv对胰蛋白酶消化的敏感性增加表明结合活性的缺乏是由Q6E突变体的不正确折叠引起的。基于两类VH序列之间的比较，将三个额外的IA类衍生的FR 1残基移植到“缺陷”亚组IIA序列上，部分恢复了含Q6E的scFv的抗原结合活性。我们的结果表明，重链的残基6可能是折叠核的一部分，涉及框架区1的前两条P链，不同抗体家族中6位谷氨酰胺或谷氨酸的进化保守性很可能表明，在免疫球蛋白VH结构域内，进化了不同家族特异性折叠核。
While studying the expression of single-chain antibodies (scFv) derived from several murine monoclonal antibodies, we found that residue 6 in Framework region 1 of the heavy chain variable domain plays a crucial role in antibody folding. Binding activity of three murine antibodies with a heavy chain variable region (VH) subgroup IIA was completely lost when at this position the mild-type residue glutamine (Q) was substituted by glutamate (E), Increased sensitivity towards trypsin digestion of soluble scFv suggested that the lack of binding activity was caused by incorrect folding of Q6E mutants. Grafting of the three additional class IA derived FR1 residues, based upon the comparison between both classes of VH sequences, on to the 'defect' subgroup IIA sequence, partially restored the antigen binding activity of the Q6E-containing scFv, Our results suggest that residue 6 of the heavy chain may be part of a folding nucleus, involving the first two P-strands of Framework region 1, The evolutionary conservation of either glutamine or glutamate at position 6 in different antibody families may well indicate that within immunoglobulin VH domains, different family specific folding nuclei have evolved.