Evidence for regulated coupling of A1 adenosine receptors by phosphorylation in Zucker rats.
Evidence for regulated coupling of A1 adenosine receptors by phosphorylation in Zucker rats.
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Zucker 大鼠中通过磷酸化调节 A1 腺苷受体偶联的证据。
DOI：
10.1152/ajpendo.1995.268.4.e693
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
LaNoue,KF
中科院分区：
文献类型：
--
作者：
Berkich,DA;Luthin,DR;Woodard,RL;Vannucci,SJ;Linden,J;LaNoue,KF
研究旨在为之前观察到的肥胖脂肪细胞中脂肪分解不那么活跃而A1腺苷受体信号更活跃的分子基础找到分子基础。用定量免疫印迹法检测，肥胖组Giα1和Gsα45水平与瘦膜(分别为50%和30%)相比异常低，但其他Gα亚单位水平正常。然而，当评估1)在腺苷受体激动剂存在的情况下，GTP抑制Forsklin刺激的腺酰环化酶的能力，以及2)非水解性鸟嘌呤核苷酸类似物改变A1腺苷受体激动剂结合的能力时，肥胖者的受体-Gi蛋白对GTP的敏感度大约是瘦膜的5-10倍。碱性磷酸酶处理肥胖但不瘦动物的分离脂肪细胞膜降低了鸟嘌呤核苷酸激动剂结合的敏感性。令人惊讶的是，所有动物的溶解脂肪细胞A1腺苷受体对鸟嘌呤核苷酸表现出与完整肥胖膜相同的高敏感性，而且这种高敏感性可以通过碱性磷酸酶处理降低20倍。这些数据表明，蛋白质磷酸化可能调节大鼠脂肪细胞膜上A1腺苷受体的偶联。
Studies were designed to find the molecular basis for previous observations that lipolysis is less active and A1 adenosine receptor signaling is more active in adipocytes from obese than from lean Zucker rats. With quantitative immunoblot procedures for detection, Gi alpha 1 and Gs alpha 45 levels were found anomalously low in obese compared with lean membranes (50 and 30%, respectively), but other G alpha subunit levels were normal. However, the sensitivity of the receptor-Gi protein to GTP was about 5- to 10-fold higher in obese compared with lean membranes when assessed from 1) the ability of GTP to inhibit forskolin-stimulated adenylyl cyclase in the presence of an adenosine receptor agonist and 2) the ability of a nonhydrolyzable guanine nucleotide analogue to alter A1 adenosine receptor agonist binding. Alkaline phosphatase treatment of isolated adipocyte membranes from obese but not lean animals decreased guanine nucleotide sensitivity of agonist binding. Surprisingly, solubilized adipocyte A1 adenosine receptors from all animals exhibited the same high sensitivity to guanine nucleotides as that of intact obese membranes, and this high sensitivity could be decreased 20-fold by treatment with alkaline phosphatase. These data suggest that protein phosphorylation may regulate coupling of the A1 adenosine receptor in rat adipocyte membranes.