Sanders M A, LeVine H
Department of Biology, University of Michigan, Ann Arbor, USA.
J Neurochem. 1996 Dec;67(6):2362-72. doi: 10.1046/j.1471-4159.1996.67062362.x.
The carboxy-terminal cytoplasmic regions of the rat neurokinin 1 (substance P) and neurokinin 2 (neurokinin A) receptors have been exchanged to determine if this region of the neurokinin 1 receptor is involved in its desensitization. When expressed at similar levels in stably transfected Chinese hamster ovary (CHO) cell lines, receptors containing the carboxy-terminal region of the neurokinin 1 receptor desensitized significantly more (as measured by reduction of the inositol 1,4,5-trisphosphate response) when preexposed for 1 min to 1 microM neurokinin, indicating a role for the carboxy-terminal region of the neurokinin 1 receptor in its desensitization. Measurement of receptor internalization using radiolabeled neurokinins (0.3 nM) indicated that approximately 75-80% of the receptors were internalized in each cell line after 10 min at 37 degrees C, with no observable correlation between neurokinin receptor desensitization and internalization. Measurement of loss of receptor surface sites for cell lines CHO NK1 and CHO NK1NK2 following exposure to 1 microM substance P also indicated no obvious relationship between the percent desensitization and percent of receptors internalized. Also, two inhibitors of neurokinin 1 receptor internalization, phenylarsine oxide and hyperosmolar sucrose, did not inhibit neurokinin 1 receptor desensitization. The protein kinase inhibitors Ro 31-8220, staurosporine, and Zn2+ had no effect on neurokinin 1 receptor desensitization, indicating that the kinases affected by these agents are not rate-limiting in neurokinin 1 receptor desensitization in this system.
已将大鼠神经激肽1（P物质）和神经激肽2（神经激肽A）受体的羧基末端胞质区域进行交换，以确定神经激肽1受体的该区域是否参与其脱敏过程。当在稳定转染的中国仓鼠卵巢（CHO）细胞系中以相似水平表达时，含有神经激肽1受体羧基末端区域的受体在预先暴露于1μM神经激肽1分钟后，脱敏程度明显更高（通过肌醇1,4,5 -三磷酸反应的降低来衡量），这表明神经激肽1受体的羧基末端区域在其脱敏过程中起作用。使用放射性标记的神经激肽（0.3 nM）测量受体内化情况表明，在37℃下孵育10分钟后，每个细胞系中约75 - 80%的受体发生内化，神经激肽受体脱敏与内化之间未观察到相关性。测量CHO NK1和CHO NK1NK2细胞系在暴露于1μM P物质后受体表面位点的丧失情况，也表明脱敏百分比与内化受体百分比之间没有明显关系。此外，两种神经激肽1受体内化抑制剂，氧化苯胂和高渗蔗糖，并未抑制神经激肽1受体脱敏。蛋白激酶抑制剂Ro 31 - 8220、星形孢菌素和Zn2 +对神经激肽1受体脱敏没有影响，这表明这些药物所影响的激酶在该系统中不是神经激肽1受体脱敏的限速因素。
