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首页> 外文期刊>American Journal of Physiology >Inversion of both gating polarity and CO2 sensitivity of voltage gating with D3N mutation of Cx50.
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Inversion of both gating polarity and CO2 sensitivity of voltage gating with D3N mutation of Cx50.

机译：带有Cx50的D3N突变的电压门控的门控极性和CO2灵敏度的反转。

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摘要

The effect of CO(2)-induced acidification on transjunctional voltage (V(j)) gating was studied by dual voltage-clamp in oocytes expressing mouse connexin 50 (Cx50) or a Cx50 mutant (Cx50-D3N), in which the third residue, aspartate (D), was mutated to asparagine (N). This mutation inverted the gating polarity of Cx50 from positive to negative. CO(2) application greatly decreased the V(j) sensitivity of Cx50 channels, and increased that of Cx50-D3N channels. CO(2) also affected the kinetics of V(j) dependent inactivation of junctional current (I(j)), decreasing the gating speed of Cx50 channels and increasing that of Cx50-D3N channels. In addition, the D3N mutation increased the CO(2) sensitivity of chemical gating such that even CO(2) concentrations as low as 2.5% significantly lowered junctional conductance (G(j)). With Cx50 channels G(j) dropped by 78% with a drop in intracellular pH (pH(i)) to 6.83, whereas with Cx50-D3N channels G(j) dropped by 95% with a drop in pH(i) to just 7.19. We have previously hypothesized that the way in which V(j) gating reacts to CO(2) might be related to connexin's gating polarity. This hypothesis is confirmed here by evidence that the D3N mutation inverts the gating polarity as well as the effect of CO(2) on V(j) gating sensitivity and speed.
机译：通过双电压钳研究表达小鼠连接蛋白50（Cx50）或Cx50突变体（Cx50-D3N）的卵母细胞中CO（2）诱导的酸化对跨结电压（V（j））门控的影响。残基天冬氨酸（D）被突变为天冬酰胺（N）。此突变将Cx50的门控极性从正反转为负。 CO（2）应用大大降低了Cx50通道的V（j）灵敏度，并增加了Cx50-D3N通道的V（j）灵敏度。 CO（2）还影响了依赖V（j）的结电流（I（j））失活的动力学，降低了Cx50通道的门控速度，并增加了Cx50-D3N通道的门控速度。此外，D3N突变增加了化学门控对CO（2）的敏感性，因此即使低至2.5％的CO（2）浓度也显着降低了连接电导（G（j））。 Cx50通道的G（j）下降78％，而细胞内pH（pH（i））下降至6.83，而Cx50-D3N通道的G（j）下降95％，pH（i）下降至7.19。我们先前曾假设，V（j）门控与CO（2）反应的方式可能与连接蛋白的门控极性有关。此假设在这里通过D3N突变会反转门控极性以及CO（2）对V（j）门控灵敏度和速度的影响得到证实。

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