REGULATION OF HORMONE-RESPONSIVE ADENYLATE CYCLASE

神经肽Y（NPY）与MC-IXC细胞上的Y1亚型受体结合，并与MC-IXC细胞上的Y1亚型受体结合 SMS-MSN上的Y2受体，两种人神经母细胞瘤细胞系。NPY抑制 腺苷酸环化酶在MC-IXC细胞中表达，而在SMS-MSN细胞中不表达。两种细胞中的NPY结合 细胞系被百日咳毒素所抑制，百日咳毒素可使41 kDalton G 两者的蛋白质。用G-α特异性抗体进行蛋白质印迹 亚基显示，MC-IX具有Gi（α），即MC-IX的抑制性G蛋白。 腺苷酸环化酶，而SMS-MSN具有Gi（α）和Go（α）， 与离子通道的激活有关因此，Y1受体 似乎介导腺苷酸环化酶和Y2的抑制，离子激活 渠道与其他β-肾上腺素能反应细胞系相反， 具有β 2-肾上腺素能受体（β 2 AR），SK-N-MC具有β 1 AR， 当暴露于激动剂时经历不寻常的脱敏。没有 B1 AR或最大激动剂刺激的腺苷酸环化酶活性丧失， 剂量反应的变化，可以通过孵育膜来模拟 与ATP和环腺苷酸依赖性蛋白激酶的催化亚基 （PKA）.脱敏作用在渗透性细胞中被一种特异性的 PKA抑制剂，但不是β AR激酶抑制剂。大规模 从大鼠纹状体中分离纯化了多巴胺D1受体 纯化的受体用于获得肽序列， 抗体，最终是受体基因。后者将有助于 识别在疾病状态下发生的受体缺陷。在 在肾脏中，与腺苷酸环化酶偶联的D1受体与 钠转运的调节。多巴胺不能刺激腺苷酸 自发性高血压大鼠近曲小管环化酶的研究 尽管该酶对其它效应物的反应正常。作为结合 活性和表观分子量的肾受体从 高血压大鼠是正常的，似乎D1受体是正常的。 它们与刺激性G蛋白偶联的能力有缺陷， 腺苷酸环化酶

Neuropeptide Y (NPY) binds to Y1-subtype receptors on MC-IXC cells and to Y2 receptors on SMS-MSN, two human neuroblastoma cell lines. NPY inhibits adenylate cyclase in MC-IXC but not SMS-MSN cells. NPY binding in both cell lines is inhibited by pertussis toxin, which ADP-ribosylates 4l kDalton G proteins in both. Western blotting with specific antibodies to G-alpha subunits showed that MC-IX has Gi(alpha), the inhibitory G protein of adenylate cyclase whereas SMS-MSN has both Gi(alpha) and Go(alpha), which has been implicated in activation of ion channels. Thus, Y1 receptors appear to mediate inhibition of adenylate cyclase and Y2, activation of ion channels. In contrast to other beta-adrenergic responsive cell lines which have beta2-adrenergic receptors (beta 2 AR), SK-N-MC have beta1 AR and undergo an unusual desensitization when exposed to agonists. There is no loss of B1 AR or maximum agonist-stimulated adenylate cyclase activity but a shift in the dose response which can be mimicked by incubating membranes with ATP and the catalytic subunit of cyclic AMP-dependent protein kinase (PKA). Desensitization is blocked in permeable cells by a specific inhibitor of PKA but not an inhibitor of beta AR kinase. A large-scale purification of the dopamine D1 receptor from rat striatum has been carried out and the purified receptor is being used to obtain peptide sequences, antibodies, and eventually the receptor gene. The latter will be useful for identifying defects in the receptor that occur in disease states. In kidney, D1 receptors coupled to adenylate cyclase have been implicated in regulation of sodium transport. Dopamine fails to stimulate adenylate cyclase in proximal convoluted tubules from spontaneous hypertensive rats although the enzyme responds normally to other effectors. As the binding activity and apparent molecular weight of the kidney receptors from the hypertensive rats are normal, it appears that the D1 receptors are defective in their ability to couple to the stimulatory G protein of adenylate cyclase.