Homologous desensitization of adenylate cyclase is associated with phosphorylation of the beta-adrenergic receptor.
Homologous desensitization of adenylate cyclase is associated with phosphorylation of the beta-adrenergic receptor.
复制标题
腺苷酸环化酶的同源脱敏与β-肾上腺素能受体的磷酸化有关。
DOI：
10.1016/s0021-9258(18)89201-8
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
R. Lefkowitz
中科院分区：
文献类型：
--
作者：
D. Sibley;R. Strasser;M. Caron;R. Lefkowitz
我们最近证明，火鸡红细胞中腺苷酸环化酶的异源脱敏与β-肾上腺素能受体的磷酸化高度相关。相比之下，我们对β-肾上腺素能受体脱敏同源形式的生化机制知之甚少，这种脱敏是激动剂特异性的，而不是cAMP介导的。因此，目前的研究旨在检查β-肾上腺素能受体的磷酸化是否也与经过充分研究的模型系统（青蛙红细胞）中的这种形式的脱敏有关。这些细胞与 β-肾上腺素能激动剂异丙肾上腺素预孵育会导致异丙肾上腺素刺激的腺苷酸环化酶活性下降 45%，而基础、前列腺素 E1-、NaF-、鸟苷酸 5'-基亚胺二磷酸、毛喉素或 MnCl2 刺激的酶活性没有显着变化。 [125I]碘氰吲哚洛尔膜结合位点也减少了 48%。相反，细胞与前列腺素E1预孵育仅减弱前列腺素E1刺激的酶活性，并且不影响[125I]碘氰吲哚洛尔结合。通过将细胞与 32Pi 预孵育并使它们脱敏，然后通过亲和层析纯化受体来评估 β-肾上腺素能受体的磷酸化。在基础条件下，每摩尔受体含有约 0.62 摩尔磷酸盐，而用异丙肾上腺素脱敏后，磷酸盐增加至 1.9 摩尔/摩尔。这种异丙肾上腺素诱导的受体磷酸化表现出立体特异性，并被β-肾上腺素能拮抗剂普萘洛尔阻断。此外，与前列腺素 E1 预孵育不会促进 β-肾上腺素能受体磷酸化。这些数据表明受体磷酸化涉及同源以及异源形式的脱敏，并且可能为腺苷酸环化酶偶联激素受体的脱敏提供统一的机制。
We recently demonstrated that heterologous desensitization of adenylate cyclase in turkey erythrocytes is highly correlated with phosphorylation of the beta-adrenergic receptor. In contrast, little is known of the biochemical mechanisms underlying the homologous form of beta-adrenergic receptor desensitization, which is agonist-specific and not cAMP-mediated. Accordingly, the present studies were undertaken to examine if phosphorylation of the beta-adrenergic receptor is also associated with this form of desensitization in a well studied model system, the frog erythrocyte. Preincubation of these cells with the beta-adrenergic agonist isoproterenol leads to a 45% decline in isoproterenol-stimulated adenylate cyclase activity without significant changes in basal, prostaglandin E1-, NaF-, guanyl-5'-yl-imidodiphosphate-, forskolin-, or MnCl2-stimulated enzyme activities. There is also a 48% decline in [125I]iodocyanopindolol membrane binding sites. Conversely, preincubation of the cells with prostaglandin E1 attenuates only the prostaglandin E1-stimulated enzyme activity and does not affect [125I]iodocyanopindolol binding. Phosphorylation of the beta-adrenergic receptor was assessed by preincubating the cells with 32Pi and desensitizing them, and subsequently purifying the receptors by affinity chromatography. Under basal conditions there is about 0.62 mol of phosphate/mol of receptor whereas after desensitization with isoproterenol this increases to 1.9 mol/mol. This isoproterenol-induced receptor phosphorylation exhibits stereospecificity and is blocked by the beta-adrenergic antagonist propranolol. In addition, preincubation with prostaglandin E1 does not promote beta-adrenergic receptor phosphorylation. These data suggest that receptor phosphorylation is involved in homologous as well as heterologous forms of desensitization and may provide a unifying mechanism for desensitization of adenylate cyclase-coupled hormone receptors.