Folding of the conserved domain but not of flanking regions in the integrin beta(2) subunit requires association with the alpha subunit
Folding of the conserved domain but not of flanking regions in the integrin beta(2) subunit requires association with the alpha subunit
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DOI：
10.1073/pnas.94.7.3156
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发表时间：
1997-04-01
影响因子：
11.1
通讯作者：
Springer, TA
中科院分区：
文献类型：
--
作者：
Huang, CC;Lu, CF;Springer, TA
我们用单克隆抗体免疫沉淀法来探测淋巴细胞功能相关抗原1 β 2整合素亚基生物合成过程中的折叠（LFA-1;在β（2）亚基中氨基酸残基102和344之间存在进化上保守的区域，mAb针对保守区域之前的一个亚区，和保守结构域后的两个亚区，免疫沉淀了未结合的β（2）'前体和成熟的α（L）/β（2）复合物，表明这些亚区的部分在与α（L）结合之前被折叠。C-末端富含半胱氨酸区域的活化mAb KIM 127优先结合未结合的β亚基，表明其可能结合未活化LFA-1中α β界面中的表位。相比之下，针对保守区中五个不同表位的mAb不与未缔合的β（2）'前体反应，表明该区域在α（L）缔合后折叠，并且与α（L）/β（2）复合物中的α（L）亚基密切缔合。涉及保守区和C-末端区段之间边界的两个不同表位的mAb与β（2）'前体完全或部分反应，表明该区域在与α（L）结合之前部分折叠。研究结果表明，保守区是一个独特的折叠，因此结构单位，并与α亚基密切相关。
We have used immunoprecipitation with mAbs to probe folding during biosynthesis of the beta(2) integrin subunit of lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18) before and after association with the alpha(L) subunit, An evolutionarily conserved region is present in the beta(2) subunit between amino acid residues 102 and 344, mAbs to one subregion before the conserved region, and two subregions after the conserved domain, immunoprecipitated both the unassociated beta(2)' precursor and mature alpha(L)/beta(2) complex, suggesting portions of these subregions are folded before association with alpha(L). An activating mAb to the C-terminal cysteine-rich region, KIM127, preferentially bound to the unassociated beta subunit, suggesting that it may bind to an epitope that is in an alpha beta interface in unactivated LFA-1. By contrast, mAbs to five different epitopes in the conserved region did not react with unassociated beta(2)' precursor, suggesting that this region folds after alpha(L) association and is intimately associated with the alpha(L) subunit in the alpha(L)/beta(2) complex. mAbs to two different epitopes that involve the border between the conserved region and the C-terminal segment, were fully or partially reactive with the beta(2)' precursor, suggesting that this region is partially folded before association with alpha(L). The findings suggest that the conserved region is a distinct folding and hence structural unit, and is intimately associated with the alpha subunit.