OXYTOCIN STIMULATES MYOMETRIAL GUANOSINE TRIPHOSPHATASE AND PHOSPHOLIPASE-C ACTIVITIES VIA COUPLING TO G-ALPHA(Q/11)
OXYTOCIN STIMULATES MYOMETRIAL GUANOSINE TRIPHOSPHATASE AND PHOSPHOLIPASE-C ACTIVITIES VIA COUPLING TO G-ALPHA(Q/11)
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DOI：
10.1210/en.136.4.1509
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发表时间：
1995-04-01
期刊：
影响因子：
4.8
通讯作者：
SANBORN, BM
中科院分区：
文献类型：
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作者：
KU, CY;QIAN, A;SANBORN, BM
催产素刺激子宫肌层磷脂酰肌醇周转。为了阐明偶联机制是否涉及催产素受体与GTP结合蛋白的相互作用，我们研究了催产素刺激大鼠和人类子宫肌层膜中的鸟苷三磷酸酶（GTdR）活性和磷脂酶-C活性。催产素持续刺激GTP酶和磷脂酶-C的活性，并且这两种刺激都被针对GTP结合蛋白G α（q）和G α（11）羧基末端的抗体减弱。用抗原肽预孵育中和抗体可逆转这种抑制作用。[Thr（4），Gly（7）]催产素是一种特异性催产素受体激动剂，它能刺激GT3和磷脂酶C的活性，抗G α（q/11）IgG也能抑制这种刺激作用。免疫反应性GTP结合蛋白G α（q）和G α（11）以及磷脂酶C β（3）亚型存在于子宫肌层膜中。这些结果表明，子宫肌层中催产素对磷脂酶C活性的刺激是通过G α（q）、G α（11）或密切相关的GTP结合蛋白介导的，可能与磷脂酶C β偶联。
Oxytocin stimulates phosphoinositide turnover in myometrium. To elucidate whether the coupling mechanism involves the interaction of oxytocin receptor with GTP-binding proteins, we examined oxytocin stimulation of guanosine triphosphatase (GTPase) activity and phospholipase-C activity in rat and human myometrial membranes. Oxytocin consistently stimulated both GTPase and phospholipase-C activities, and both stimulations were attenuated by an antibody directed against the carboxyl-terminals of the GTP-binding proteins, G alpha(q) and G alpha(11). Neutralization of the antibody by preincubation with antigenic peptide reversed this inhibition. [Thr(4),Gly(7)]oxytocin, a specific oxytocin receptor agonist, stimulated both GTPase and phospholipase-C activities, and the stimulations were also inhibited by anti-G alpha(q/11) IgG. Immunoreactive GTP-binding proteins, G alpha(q) and G alpha(11), and phospholipase-C beta(3) isoforms were present in myometrial membranes. These results indicate that stimulation of phospholipase-C activity by oxytocin in myometrium is mediated via G alpha(q), G alpha(11), or a closely related GTP-binding protein, probably coupling to phospholipase-C beta.