PHARMACOLOGICAL CHARACTERIZATION OF GUANINE-NUCLEOTIDE EXCHANGE-REACTIONS IN MEMBRANES FROM CHO CELLS STABLY TRANSFECTED WITH HUMAN MUSCARINIC RECEPTORS M1-M4
PHARMACOLOGICAL CHARACTERIZATION OF GUANINE-NUCLEOTIDE EXCHANGE-REACTIONS IN MEMBRANES FROM CHO CELLS STABLY TRANSFECTED WITH HUMAN MUSCARINIC RECEPTORS M1-M4
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DOI：
10.1016/0024-3205(93)90301-i
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发表时间：
1993-01-01
期刊：
影响因子：
6.1
通讯作者：
BIRDSALL, NJM
中科院分区：
文献类型：
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作者：
LAZARENO, S;FARRIES, T;BIRDSALL, NJM
我们研究了毒蕈碱激动剂刺激的[S-35] GTP γ S结合和[γ P-32]GTP水解（GTP酶）在CHO细胞膜稳定转染人毒蕈碱m1-m4受体。“完全”激动剂对m2和m4受体的效力是对m1和m3的至少10倍。这种模式是不太明显的“部分”激动剂，它有一个更大的最大效果在m2和m4比在m1和m3。McN-A343对m4受体的作用强于对m2受体的作用。通过将抑制曲线的数据直接拟合到Schild模型来估计拮抗剂亲和力常数。拮抗剂亲和力估计值与早期使用动物组织进行的结合研究中测量的值非常相似，并证实了对托吡卡胺和secoverine的小程度的m4选择性。受体亚型激活多于一种G蛋白亚型，m2和m4受体仅激活百日咳（PTX）敏感的G蛋白，而m1和m3与PTX敏感和不敏感的G蛋白偶联。乙酰胆碱（ACh）更有力地刺激鸟嘌呤核苷酸交换在PTX处理的ml细胞比对照。
We have studied muscarinic agonist stimulated [S-35]GTPgammaS binding and [gammaP-32]GTP hydrolysis (GTPase) in membranes from CHO cells stably transfected with human muscarinic m1-m4 receptors. 'Full' agonists were at least 10-fold more potent at m2 & m4 receptors than at ml & m3. This pattern was less marked with 'partial' agonists, which had a greater maximal effect at m2 & m4 than at m1 & m3. McN-A343 uniquely was more potent and efficacious at m4 than at m2 receptors, Antagonist affinity constants were estimated by fitting the data from inhibition curves directly to the Schild model. Antagonist affinity estimates were very similar to those measured earlier in binding studies using animal tissues, and confirmed a small degree of m4 selectivity for tropicamide and secoverine. The receptor subtypes activated more than one G-protein subtype, m2 & m4 receptors activated only pertussis (PTX) sensitive G-proteins, while ml & m3 coupled to both PTX sensitive and insensitive G-proteins. Acetylcholine (ACh) was more potent in stimulating guanine nucleotide exchange in PTX treated ml cells than in controls.