Gurevich V V, Dion S B, Onorato J J, Ptasienski J, Kim C M, Sterne-Marr R, Hosey M M, Benovic J L
Department of Pharmacology, Northwestern University Medical School, Chicago, Illinois 60611.
J Biol Chem. 1995 Jan 13;270(2):720-31. doi: 10.1074/jbc.270.2.720.
Arrestins play an important role in quenching signal transduction initiated by G protein-coupled receptors. To explore the specificity of arrestin-receptor interaction, we have characterized the ability of various wild-type arrestins to bind to rhodopsin, the beta 2-adrenergic receptor (beta 2AR), and the m2 muscarinic cholinergic receptor (m2 mAChR). Visual arrestin was found to be the most selective arrestin since it discriminated best between the three different receptors tested (highest binding to rhodopsin) as well as between the phosphorylation and activation state of the receptor (> 10-fold higher binding to the phosphorylated light-activated form of rhodopsin compared to any other form of rhodopsin). While beta-arrestin and arrestin 3 were also found to preferentially bind to the phosphorylated activated form of a given receptor, they only modestly discriminated among the three receptors tested. To explore the structural characteristics important in arrestin function, we constructed a series of truncated and chimeric arrestins. Analysis of the binding characteristics of the various mutant arrestins suggests a common molecular mechanism involved in determining receptor binding selectivity. Structural elements that contribute to arrestin binding include: 1) a C-terminal acidic region that serves a regulatory role in controlling arrestin binding selectivity toward the phosphorylated and activated form of a receptor, without directly participating in receptor interaction; 2) a basic N-terminal domain that directly participates in receptor interaction and appears to serve a regulatory role via intramolecular interaction with the C-terminal acidic region; and 3) two centrally localized domains that are directly involved in determining receptor binding specificity and selectivity. A comparative structure-function model of all arrestins and a kinetic model of beta-arrestin and arrestin 3 interaction with receptors are proposed.
抑制蛋白在终止由G蛋白偶联受体引发的信号转导过程中发挥着重要作用。为了探究抑制蛋白与受体相互作用的特异性，我们对多种野生型抑制蛋白与视紫红质、β2 - 肾上腺素能受体（β2AR）以及M2毒蕈碱型胆碱能受体（M2 mAChR）的结合能力进行了表征。视蛋白抑制蛋白被发现是最具选择性的抑制蛋白，因为它在测试的三种不同受体之间（与视紫红质的结合力最高）以及受体的磷酸化和激活状态之间的区分能力最强（与磷酸化的光激活形式的视紫红质的结合力比其他任何形式的视紫红质高10倍以上）。虽然β - 抑制蛋白和抑制蛋白3也被发现优先结合给定受体的磷酸化激活形式，但它们在测试的三种受体之间的区分能力较弱。为了探究抑制蛋白功能中重要的结构特征，我们构建了一系列截短和嵌合的抑制蛋白。对各种突变抑制蛋白结合特性的分析表明，存在一种共同的分子机制参与决定受体结合选择性。有助于抑制蛋白结合的结构元件包括：1）一个C末端酸性区域，其在控制抑制蛋白对受体磷酸化和激活形式的结合选择性方面起调节作用，但不直接参与受体相互作用；2）一个碱性N末端结构域，其直接参与受体相互作用，并且似乎通过与C末端酸性区域的分子内相互作用起到调节作用；3）两个位于中央的结构域，它们直接参与决定受体结合特异性和选择性。提出了所有抑制蛋白的比较结构 - 功能模型以及β - 抑制蛋白和抑制蛋白3与受体相互作用的动力学模型。
