Functional coupling of GABAB receptors with G proteins that are sensitive to N-ethylmaleimide treatment, suramin, and benzalkonium chloride in rat cerebral cortical membranes
Functional coupling of GABAB receptors with G proteins that are sensitive to N-ethylmaleimide treatment, suramin, and benzalkonium chloride in rat cerebral cortical membranes
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DOI：
10.1007/s007020070024
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发表时间：
2000-01-01
影响因子：
3.3
通讯作者：
Koyama, T
中科院分区：
文献类型：
--
作者：
Odagaki, Y;Nishi, N;Koyama, T
虽然已知GABA(B)受体与腺苷酸环化酶负偶联，但GABA(B)受体与G(i)亚家族成员之间功能相互作用的详细选择性仍然不明确。（+/-）-巴氯芬刺激的高亲和力GTPase活性，被2-羟基-saclofen竞争性拮抗，通过n-乙基马来酰亚胺（NEM）预处理膜以浓度和潜伏期依赖的方式减弱。nem预处理（50 muM, 4℃15 min）的膜与百日咳毒素敏感的牛脑G蛋白重组后，恢复了(+/-)-巴氯芬敏感的高亲和力GTPase活性。重组大鼠G（α）亚基中，G（i α -2）比其他亚基(G(i α -2) > G(i α -3) > G（i α -1) = G(o α)）效果更好。100 muM苏拉明和100 muM苯扎氯铵也完全消除了GABA(B)受体介导的高亲和力GTPase活性。这些结果表明，大鼠大脑皮层的GABA(B)受体与nem敏感的G蛋白偶联，特别是对苏拉明和苯扎氯铵敏感的G（i2）。
Although it is known that GABA(B) receptors are negatively coupled to adenylyl cyclase, the detailed selectivity of functional interaction between GABA(B) receptors and G(i) subfamily members is still ambiguous. (+/-)-Baclofen-stimulated high-affinity GTPase activity, which was competitively antagonized by 2-hydroxy-saclofen, was attenuated by pretreatment of the membranes with N-ethylmaleimide (NEM) in a concentration- and incubation period-dependent manner. The NEM-pretreated (50 muM, 15 min at 4 degreesC) membranes restored the (+/-)-baclofen-sensitive high-affinity GTPase activity when reconstituted with pertussis toxin-sensitive bovine brain G proteins. Among recombinant rat G(alpha) subunits, G(i alpha -2) appeared most effective as compared with other subunits (G(i alpha -2) > G(i alpha -3) > G(i alpha -1) = G(o alpha)). The GABA(B) receptor-mediated high-affinity GTPase activity was also completely eliminated by 100 muM suramin and by 100 muM benzalkonium chloride. These results indicate that GABA(B) receptors in rat cerebral cortex couple to NEM-sensitive G proteins, in particular G(i2), which are sensitive to suramin and benzalkonium chloride.