Tyrosine Phosphorylation as a Conformational Switch A CASE STUDY OF INTEGRIN β3 CYTOPLASMIC TAIL
Tyrosine Phosphorylation as a Conformational Switch A CASE STUDY OF INTEGRIN β3 CYTOPLASMIC TAIL
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DOI：
10.1074/jbc.m111.231951
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发表时间：
2011-11-25
影响因子：
4.8
通讯作者：
Vinogradova, Olga
中科院分区：
文献类型：
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作者：
Deshmukh, Lalit;Meller, Nahum;Vinogradova, Olga
可逆的蛋白质磷酸化对于许多基本的细胞过程至关重要。添加和去除磷酸基团的实际影响有三重：局部/全局几何形状的变化、静电势的改变以及两者的结果，改变了蛋白质-靶标相互作用。在这里，我们对磷酸化对关键细胞表面受体α(IIb)β(3)整合素的构象和功能状态的影响进行了全面的结构研究。我们主要通过 NMR 分析了磷酸化（Tyr（747）和 Tyr（759））β（3）整合素细胞质尾（CT），我们的数据表明在水性和膜模拟条件下，磷酸化会导致大量构象重排。这些变化源自新的离子相互作用和修改的磷脂结合。在水性条件下，关键的 Tyr(747) 磷酸化可防止 β 3CT 与其异二聚体伴侣 α IIbCT 结合，从而可能维持受体的激活状态。这一结论经过体内测试并通过整合素依赖性内皮细胞粘附测定得到证实。在膜模拟条件下，磷酸化会导致膜嵌入发生改变，其特征是二级结构模式和 β 3CT 整体折叠发生显着变化。总的来说，这些数据为磷酸化的多种调节作用提供了独特的分子见解。
Reversible protein phosphorylation is vital for many fundamental cellular processes. The actual impact of adding and removing phosphate group(s) is 3-fold: changes in the local/global geometry, alterations in the electrostatic potential and, as the result of both, modified protein-target interactions. Here we present a comprehensive structural investigation of the effects of phosphorylation on the conformational as well as functional states of a crucial cell surface receptor, alpha(IIb)beta(3) integrin. We have analyzed phosphorylated (Tyr(747) and Tyr(759)) beta(3) integrin cytoplasmic tail (CT) primarily by NMR, and our data demonstrate that under both aqueous and membrane-mimetic conditions, phosphorylation causes substantial conformational rearrangements. These changes originate from novel ionic interactions and revised phospholipid binding. Under aqueous conditions, the critical Tyr(747) phosphorylation prevents beta 3CT from binding to its heterodimer partner alpha IIbCT, thus likely maintaining an activated state of the receptor. This conclusion was tested in vivo and confirmed by integrin-dependent endothelial cells adhesion assay. Under membrane-mimetic conditions, phosphorylation results in a modified membrane embedding characterized by significant changes in the secondary structure pattern and the overall fold of beta 3CT. Collectively these data provide unique molecular insights into multiple regulatory roles of phosphorylation.