A chloride channel from lobster walking leg nerves. Characterization of single-channel properties in planar bilayers.
A chloride channel from lobster walking leg nerves. Characterization of single-channel properties in planar bilayers.
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龙虾行走腿神经的氯化物通道。平面双层中单通道特性的表征。
DOI：
10.1085/jgp.96.4.707
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发表时间：
1990-10
期刊：
影响因子：
--
通讯作者：
Moczydlowski E
中科院分区：
文献类型：
--
作者：
Lukács GL;Moczydlowski E
通过将龙虾步行腿神经质膜制备物掺入平面双层中，表征了一种新型、电导率小的氯离子通道。在对称的100 mM NaCl，10 mM Tris-HCl，pH 7.4的条件下，单个Cl-通道表现出整流电流-电压（I-V）行为，在正电压下电导为19.2 +/- 0.8 pS，在-40至0 mV电压范围内电导为15.1 +/- 1.6 pS。与Cl-相比，该通道对Na+的渗透性可忽略不计，并且在接近双离子条件下测量的阴离子渗透性相对于Cl-的顺序如下：我...（2.7）大于NO3-（1.8）大于Br-（1.5）大于Cl-（1.0）大于CH 3CO 2-（0.18）大于HCO 3-（0.10）大于葡萄糖酸盐（0.06）大于F-（0.05）。在正电压下，单位电导以Michaelis-Menten方式随着Cl-浓度的增加而饱和，Km为100 mM，γ max = 33 pS。I-V曲线在10 mM Tris或10 mM HEPES缓冲液中相似，但在顺式侧用100 mM四乙基氯化铵取代100 mM NaCl导致整流增加，在负电压下电流降低40%。通道的门控是弱电压依赖性的，在-75 mV和+75 mV时的开放状态概率分别为0.23和0.64。通道门控对顺式pH敏感，对于7.4至11的pH变化观察到打开概率增加，对于7.4至6.0的pH变化观察到几乎完全抑制。龙虾Cl-通道可被阴离子转运抑制剂SITS（4-乙酰氨基，4 '-异硫氰基芪-2，2'-二磺酸）和NPPB（5-硝基-2-（3-苯基丙基氨基）苯甲酸）可逆阻断。这些特征中的许多与先前描述的各种脊椎动物细胞（包括上皮细胞）中的小电导Cl-通道的特征相似。这些功能的比较表明，这种无脊椎动物的Cl-通道是一个广泛分布的小电导阴离子通道类的进化原型。
A novel, small conductance of Cl- channel was characterized by incorporation into planar bilayers from a plasma membrane preparation of lobster walking leg nerves. Under conditions of symmetrical 100 mM NaCl, 10 mM Tris-HCl, pH 7.4, single Cl- channels exhibit rectifying current-voltage (I-V) behavior with a conductance of 19.2 +/- 0.8 pS at positive voltages and 15.1 +/- 1.6 pS in the voltage range of -40 to 0 mV. The channel exhibits a negligible permeability for Na+ compared with Cl- and displays the following sequence of anion permeability relative to Cl- as measured under near bi-ionic conditions: I- (2.7) greater than NO3- (1.8) greater than Br- (1.5) greater than Cl- (1.0) greater than CH3CO2- (0.18) greater than HCO3- (0.10) greater than gluconate (0.06) greater than F- (0.05). The unitary conductance saturates with increasing Cl- concentration in a Michaelis-Menten fashion with a Km of 100 mM and gamma max = 33 pS at positive voltage. The I-V curve is similar in 10 mM Tris or 10 mM HEPES buffer, but substitution of 100 mM NaCl with 100 mM tetraethylammonium chloride on the cis side results in increased rectification with a 40% reduction in current at negative voltages. The gating of the channel is weakly voltage dependent with an open-state probability of 0.23 at -75 mV and 0.64 at +75 mV. Channel gating is sensitive to cis pH with an increased opening probability observed for a pH change of 7.4 to 11 and nearly complete inhibition for a pH change of 7.4 to 6.0. The lobster Cl- channel is reversibly blocked by the anion transport inhibitors, SITS (4-acetamido, 4'-isothiocyanostilbene-2,2'-disulfonic acid) and NPPB (5- nitro-2-(3-phenylpropylamino)benzoic acid). Many of these characteristics are similar to those previously described for small conductance Cl- channels in various vertebrate cells, including epithelia. These functional comparisons suggest that this invertebrate Cl- channel is an evolutionary prototype of a widely distributed class of small conductance anion channels.