On the role of endogenous G-protein βγ subunits in N-type Ca2+ current inhibition by neurotransmitters in rat sympathetic neurones
On the role of endogenous G-protein βγ subunits in N-type Ca2+ current inhibition by neurotransmitters in rat sympathetic neurones
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DOI：
10.1111/j.1469-7793.1998.319bw.x
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发表时间：
1998-01-15
影响因子：
5.5
通讯作者：
Buckley, NJ
中科院分区：
文献类型：
--
作者：
Delmas, P;Brown, DA;Buckley, NJ
1. 利用全细胞和穿孔贴片记录，我们研究了内源性g蛋白β - γ亚单位在神经递质介导的解离大鼠颈上交感神经元n型Ca2+通道电流（I-Ca）的抑制中所起的作用。-肾上腺素能受体激酶1的g端结构域的表达。（β ARK1），包含与G β γ结合的共识基基（QXXER），降低了去甲肾上腺素和生长抑素对I-Ca的快速（百日毒（PTX）敏感）和电压依赖性抑制，但不降低血管紧张素II诱导的缓慢（PTX不敏感）和电压依赖性抑制。β ARK1肽降低了gtp - γ -s诱导的电压依赖性和ptx敏感的I-Ca抑制，但不降低gtp - γ -s介导的电压依赖性抑制。G β (1) γ(2)的过表达，通过降低I-Ca密度和增强基础便利化来模拟电压依赖性抑制，阻断了电压依赖性去甲肾上腺素和生长抑素介导的抑制，但不阻断血管紧张素ii介导的抑制。β - ARK1 c端β(1)和γ(2)亚基的go表达阻止了G β - γ二聚体对基础Ca2+通道行为的影响，其方式与G β - γ的隔离一致。β - ARK1的c端表达减缓了I-Ca在调节去极化后的抑制动力学，并通过累积隔离β - γ亚基诱导了持久的促进。我们的研究发现，内源性G β γ是去甲肾上腺素和生长抑素诱导的电压依赖性、ptx敏感性I-Ca抑制的中介，而不是电压依赖性、血管紧张素II诱导的ptx不敏感抑制的中介。他们还支持电压依赖性抑制是由直接的G β γ - ca2 +通道相互作用产生的观点。
1. Using whole-cell and perforated-patch recordings, we have examined the part played by endogenous G-protein beta gamma subunits in neurotransmitter-mediated inhibition of N-type Ca2+ channel current (I-Ca) in dissociated rat superior cervical sympathetic neurones.2. Expression of the G-terminus domain of beta-adrenergic receptor kinase 1. (beta ARK1), which contains the consensus motif (QXXER) for binding G beta gamma, reduced the fast (pertussis toxin (PTX)-sensitive) and voltage-dependent inhibition of I-Ca by noradrenaline and somatostatin, but not the slow (PTX-insensitive) and voltage-independent inhibition induced by angiotensin II. beta ARK1 peptide reduced GTP-gamma-S-induced voltage-dependent and PTX-sensitive inhibition of I-Ca but not GTP-gamma-S-mediated voltage-independent inhibition.3. Overexpression of G beta(1) gamma(2), which mimicked the voltage-dependent inhibition by reducing I-Ca density and enhancing basal facilitation, occluded the voltage-dependent noradrenaline-and somatostatin-mediated inhibitions but not the inhibition mediated by angiotensin II.4. Go-expression of the C-terminus of beta ARK1 with beta(1) and gamma(2) subunits prevented the effects of G beta gamma dimers on basal Ca2+ channel behaviour in a manner consistent with the sequestering of G beta gamma.5. The expression of the C-terminus of beta ARK1 slowed down reinhibition kinetics of I-Ca following conditioning depolarizations and induced long-lasting facilitation by cumulatively sequestering beta gamma subunits.6. Our findings identify endogenous G beta gamma as the mediator of the voltage-dependent, PTX-sensitive inhibition of I-Ca induced by both noradrenaline and somatostatin but not the voltage-independent, PTX-insensitive inhibition by angiotensin II. They also support the view that voltage-dependent inhibition results from a direct G beta gamma-Ca2+ channel interaction.