Functional Coupling of the γ‐Aminobutyric AcidB Receptor with Calcium Ion Channel and GTP‐Binding Protein and Its Alteration Following Solubilization of the γ‐Aminobutyric AcidB Receptor
Functional Coupling of the γ‐Aminobutyric AcidB Receptor with Calcium Ion Channel and GTP‐Binding Protein and Its Alteration Following Solubilization of the γ‐Aminobutyric AcidB Receptor
复制标题
γ-氨基丁酸B受体与钙离子通道和GTP结合蛋白的功能偶联及其在γ-氨基丁酸B受体溶解后的改变
DOI：
10.1111/j.1471-4159.1990.tb13285.x
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发表时间：
1990
影响因子：
4.7
通讯作者：
K. Kuriyama
中科院分区：
文献类型：
--
作者：
Y. Ohmori;M. Hirouchi;J. Taguchi;K. Kuriyama
摘要：使用来自牛大脑皮层的粗突触膜 (P2) 组分和脱氧胆酸钠溶解的组分，研究了 γ-氨基丁酸 (GABA)B 受体（GABA 受体的亚型之一）与钙离子通道和 GTP 结合蛋白的偶联机制。在 P2 级分中，[3H]GABA 与 GABAB 受体的结合通过添加钙离子而显着增加，并且这种增强通过钙离子通道阻滞剂（例如尼卡地平和地尔硫卓）进一步增强。相比之下，钙调蛋白拮抗剂 N-(6-氨基己基)-5-氯-1-萘磺酰胺 (W-7) 不会影响钙离子诱导的 GABAB 受体结合增强。这些结果表明 GABAB 受体可能与钙离子通道功能性偶联，钙离子通道对受体表现出抑制性调节。另一方面，GABAB受体结合被鸟嘌呤核苷酸如GTP、鸟苷5'-(3-O-硫代)三磷酸(GTPγS)、鸟苷5'-(β,γ-亚氨基)三磷酸[Gpp(NH)p]和GDP非竞争性抑制，而被(-)-巴氯芬竞争性抑制。尽管在 GTP 存在的情况下 (-)-巴氯芬对 GABAB 受体的亲和力降低，但用胰岛激活蛋白 (IAP) 预处理 P2 级分消除了 GTP 的影响。此外，GABA 和 (‐)-巴氯芬诱导 P2 部分中 GTP 酶活性的增加，并且这种增加也通过 IAP 处理而消除。这些结果表明 GABAB 受体也可能与 IAP 敏感的 GTP 结合蛋白功能性偶联。用脱氧胆酸钠处理 P2 级分，在所检测的各种去污剂中 GABAB 受体的溶解度最高。然而，溶解完全消除了钙离子和钙离子通道阻断剂的刺激作用以及GTP和GTP类似物对GABAB受体结合的抑制作用。此外，GABA 和 (-)-巴氯芬诱导的 GTP 酶活性增加在溶解后也被消除。这些结果表明，GABAB 受体与钙离子通道和 GTP 结合蛋白（例如 Ni 或 No）的功能耦合在溶解后可能很容易被破坏。
Abstract: The coupling mechanism of the γ‐Aminobutyric acid (GABA)B receptor, one of the subtypes of GABA receptors, with calcium ion channel and GTP‐binding protein was examined using a crude synaptic membrane (P2) fraction from the bovine cerebral cortex and a fraction solubilized with sodium deoxycholate. In the P2 fraction, [3H]GABA binding to the GABAB receptor was increased significantly by the addition of calcium ion, and this enhancement was accentuated further by calcium ion channel blockers such as nicardipine and diltiazem. In contrast, N‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide (W‐7), a calmodulin antagonist, did not affect on the calcium ion‐induced enhancement of GABAB receptor binding. These results suggest that the GABAB receptor may be functionally coupled with the calcium ion channel, which exhibits an inhibitory modulation against the receptor. On the other hand, GABAB receptor binding, which was noncompetitively inhibited by guanine nucleotides such as GTP, guanosine 5′‐(3‐O‐thio)triphosphate (GTPγS), guanosine 5′‐(β,γ‐imido)triphosphate [Gpp(NH)p], and GDP, was competitively inhibited by (‐)‐baclofen. Although the affinity of (‐)‐baclo‐fen for the GABAB receptor was decreased in the presence of GTP, pretreatment of the P2 fraction with islet‐activating protein (IAP) eliminated the effect of GTP. In addition, GABA and (‐)‐baclofen induced an increase of GTPase activity in the P2 fraction, and this increase was also eliminated by treatment with IAP. These results suggest that the GABAB receptor may also be functionally coupled with IAP‐sensitive GTP‐binding protein. Treatment of the P2 fraction with sodium deoxycholate resulted in the highest solubilization of GABAB receptor among various detergents examined. The solubilization, however, completely eliminated the stimulating effects of calcium ion and calcium ion channel blockers as well as the inhibitory effects of GTP and GTP analogues on GABAB receptor binding. Furthermore, the increase of GTPase activity induced by GABA and (‐)‐baclofen was also eliminated following the solubilization. These results suggest that functional coupling of the GABAB receptor with the calcium ion channel and GTP‐binding protein such as Ni or No may be easily destroyed following the solubilization.
通过胰岛激活蛋白鉴定 ADP-核糖基化的主要底物。
DOI：
--
发表时间：
1983
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Bokoch,GM;Katada,T;Northup,JK;Hewlett,EL;Gilman,AG
通讯作者：
Gilman,AG
腺苷酸环化酶的抑制性鸟嘌呤核苷酸结合调节成分的纯化和特性。
DOI：
--
发表时间：
1984
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Bokoch,GM;Katada,T;Northup,JK;Ui,M;Gilman,AG
通讯作者：
Gilman,AG