Modulation of N-type calcium channel activity by G-proteins and protein kinase C.
Modulation of N-type calcium channel activity by G-proteins and protein kinase C.
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DOI：
10.1085/jgp.115.3.277
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发表时间：
2000-03
期刊：
影响因子：
--
通讯作者：
Rittenhouse AR
中科院分区：
文献类型：
--
作者：
Barrett CF;Rittenhouse AR
大鼠上级颈神经节神经元N型电压门控性钙通道活动受多种途径调节。异源三聚体G蛋白的激活降低全细胞电流幅度，而蛋白激酶C的磷酸化导致电流幅度增加。有人提出，这两个不同的途径会聚在通道的成孔α1B亚基上，使得一个途径的作用可以排除另一个途径的作用。在这项研究中，我们的特点是进一步的行动，PKC对全细胞钡电流在新生大鼠上级颈神经节神经元。我们首先研究了G蛋白介导的抑制作用和PKC磷酸化作用是否相互排斥。通过在移液管中加入0.4 mM GTP或0.1 mM GTP-γ-S来激活G蛋白，并通过浴用500 nM佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）来激活PKC。我们发现，激活的PKC不能逆转GTP-γ-S诱导的抑制，除非施加预脉冲，表明磷酸化抑制的逆转似乎只发生在G蛋白从通道解离后。一旦抑制被解除，PKC的激活足以防止G蛋白对电流的再激活，这表明在磷酸化条件下，通道对G蛋白介导的调节具有抗性。然后，我们研究了什么样的影响，如果有的话，PKC磷酸化对N型钡电流拮抗G蛋白介导的抑制。我们发现，尽管G蛋白激活显著影响峰值电流幅度、快速失活、保持电位依赖性失活和电压依赖性激活，但当用0.1 mM GDP-β-S透析细胞质使G蛋白激活最小化时，这些参数不受PMA浴应用的影响。这些结果表明，在我们的记录条件下，PKC磷酸化对全细胞N型电流没有影响，除了防止G蛋白的抑制。
N-type voltage-gated calcium channel activity in rat superior cervical ganglion neurons is modulated by a variety of pathways. Activation of heterotrimeric G-proteins reduces whole-cell current amplitude, whereas phosphorylation by protein kinase C leads to an increase in current amplitude. It has been proposed that these two distinct pathways converge on the channel's pore-forming α1B subunit, such that the actions of one pathway can preclude those of the other. In this study, we have characterized further the actions of PKC on whole-cell barium currents in neonatal rat superior cervical ganglion neurons. We first examined whether the effects of G-protein–mediated inhibition and phosphorylation by PKC are mutually exclusive. G-proteins were activated by including 0.4 mM GTP or 0.1 mM GTP-γ-S in the pipette, and PKC was activated by bath application of 500 nM phorbol 12-myristate 13-acetate (PMA). We found that activated PKC was unable to reverse GTP-γ-S–induced inhibition unless prepulses were applied, indicating that reversal of inhibition by phosphorylation appears to occur only after dissociation of the G-protein from the channel. Once inhibition was relieved, activation of PKC was sufficient to prevent reinhibition of current by G-proteins, indicating that under phosphorylating conditions, channels are resistant to G-protein–mediated modulation. We then examined what effect, if any, phosphorylation by PKC has on N-type barium currents beyond antagonizing G-protein–mediated inhibition. We found that, although G-protein activation significantly affected peak current amplitude, fast inactivation, holding-potential–dependent inactivation, and voltage-dependent activation, when G-protein activation was minimized by dialysis of the cytoplasm with 0.1 mM GDP-β-S, these parameters were not affected by bath application of PMA. These results indicate that, under our recording conditions, phosphorylation by PKC has no effect on whole-cell N-type currents, other than preventing inhibition by G-proteins.
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影响因子：
2.5
作者：
Ehrlich, I;Elmslie, KS
通讯作者：
Elmslie, KS
影响因子：
3.4
作者：
Patil, PG;deLeon, M;Yue, DT
通讯作者：
Yue, DT
影响因子：
16.2
作者：
SWARTZ, KJ
通讯作者：
SWARTZ, KJ
DOI：
10.1073/pnas.84.12.4327
发表时间：
1987-06-01
影响因子：
11.1
作者：
MCCLESKEY, EW;FOX, AP;YOSHIKAMI, D
通讯作者：
YOSHIKAMI, D
影响因子：
6.1
作者：
HILLE, B;BEECH, DJ;WOLLMUTH, LP
通讯作者：
WOLLMUTH, LP