Conservation of the phosphate-sensitive elements in the arrestin family of proteins
Conservation of the phosphate-sensitive elements in the arrestin family of proteins
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DOI：
10.1074/jbc.m107400200
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发表时间：
2002-03-15
影响因子：
4.8
通讯作者：
Gurevich, VV
中科院分区：
文献类型：
--
作者：
Celver, J;Vishnivetskiy, SA;Gurevich, VV
抑制蛋白在G蛋白偶联受体（GPCRs）的同源脱敏中起关键作用。这些胞质蛋白选择性地结合激动剂激活和GPCR激酶磷酸化形式的GPCR，阻止其与G蛋白的进一步相互作用。视觉抑制蛋白中的某些突变产生“组成型活性”蛋白，其以高亲和力结合至视紫红质的光激活形式而不需要磷酸化。视觉抑制蛋白的晶体结构表明，这些激活突变扰乱了两组分子内相互作用，使抑制蛋白保持在其基础（非活性）状态。我们在arrestin 2和arrestin 3中引入同源突变，发现突变体在体外以磷酸化非依赖性方式与β 2肾上腺素受体结合。在非洲爪蟾卵母细胞中，相同的突变体在缺乏受体磷酸化的情况下有效地使β（2）-肾上腺素能受体和δ-阿片受体脱敏。此外，抑制蛋白突变体也脱敏的截短δ-阿片受体的C末端，含有关键的磷酸化位点，已被删除。保守的磷酸盐敏感的热点在nonvisual arrestins表明，整体折叠是类似的视觉arrestin和受体连接的磷酸盐驱动arrestin过渡到积极的结合能力状态的机制是保守的整个arrestin家族的蛋白质。
Arrestins play a key role in the homologous desensitization of G protein-coupled receptors (GPCRs). These cytosolic proteins selectively bind to the agonist-activated and GPCR kinase-phosphorylated forms of the GPCR, precluding its further interaction with the G protein. Certain mutations in visual arrestin yield "constitutively active" proteins that bind with high affinity to the light-activated form of rhodopsin without requiring phosphorylation. The crystal structure of visual arrestin shows that these activating mutations perturb two groups of intramolecular interactions that keep arrestin in its basal (inactive) state. Here we introduced homologous mutations into arrestin2 and arrestin3 and found that the resulting mutants bind to the beta(2)-adrenoreceptor in vitro in a phosphorylation-independent fashion. The same mutants effectively desensitize both the beta(2)-adrenergic and delta-opioid receptors in the absence of receptor phosphorylation in Xenopus oocytes. Moreover, the arrestin mutants also desensitize the truncated delta-opioid receptor from which the C terminus, containing critical phosphorylation sites, has been removed. Conservation of the phosphate-sensitive hot spots in nonvisual arrestins suggests that the overall fold is similar to that of visual arrestin and that the mechanisms whereby receptor-attached phosphates drive arrestin transition into the active binding competent state are conserved throughout the arrestin family of proteins.