Locking the β3 integrin I-like domain into high and low affinity conformations with disulfides
Locking the β3 integrin I-like domain into high and low affinity conformations with disulfides
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DOI：
10.1074/jbc.m312732200
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发表时间：
2004-03-12
影响因子：
4.8
通讯作者：
Springer, TA
中科院分区：
文献类型：
--
作者：
Luo, BH;Takagi, J;Springer, TA
虽然整合素α亚基I结构域存在于多种构象中，但整合素α亚基I样结构域是否经历与配体亲和力相关的α 7-螺旋结构类似的结构运动仍存在争议。二硫键被引入到β(3)整合素i样结构域，以两种不同的构象锁定其β - α - 7环和α - 7螺旋。可溶性配体结合、配体拟单抗结合和细胞粘附研究表明，二硫结合受体α (IIbbeta3)（T329C/A347C）被锁定在低亲和力状态，二硫苏糖醇处理恢复了被激活到高亲和力结合的能力；相比之下，二硫键α (IIb) β 3（V332C/M335C）被锁定在高亲和状态。结果表明，β亚基I-like结构域的激活与α亚基I结构域的激活类似，即α 7-螺旋c端方向的轴向运动与I-like结构域金属离子依赖的粘附位点重排成高亲和构象有关。
Although integrin alpha subunit I domains exist in multiple conformations, it is controversial whether integrin beta subunit I-like domains undergo structurally analogous movements of the alpha7-helix that are linked to affinity for ligand. Disulfide bonds were introduced into the beta(3) integrin I-like domain to lock its beta6-alpha7 loop and alpha7-helix in two distinct conformations. Soluble ligand binding, ligand mimetic mAb binding and cell adhesion studies showed that disulfide-bonded receptor alpha(IIbbeta3)(T329C/A347C) was locked in a low affinity state, and dithiothreitol treatment restored the capability of being activated to high affinity binding; by contrast, disulfide-bonded alpha(IIb)beta3(V332C/M335C) was locked in a high affinity state. The results suggest that activation of the beta subunit I-like domain is analogous to that of the alpha subunit I domain, i.e. that axial movement in the C-terminal direction of the alpha7-helix is linked to rearrangement of the I-like domain metal ion-dependent adhesion site into a high affinity conformation.