Subunit composition determines the single channel kinetics of the epithelial sodium channel.
Subunit composition determines the single channel kinetics of the epithelial sodium channel.
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DOI：
10.1085/jgp.112.4.423
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发表时间：
1998-10
期刊：
影响因子：
--
通讯作者：
Canessa CM
中科院分区：
文献类型：
--
作者：
Fyfe GK;Canessa CM
我们在单通道水平上进一步表征了非洲爪蟾卵母细胞中α与野生型β或γ亚基的共表达以及α与羧基末端截短的β（βT）或γ（γT）亚基共表达形成的上皮钠通道的特性。 αβ 和 αβT 通道（分别为 9.6 和 8.7 pS，150 mM Li+）被发现是组成性开放的。只有在移液管溶液中加入 1 μM 阿米洛利才能解决通道活性；两种通道类型的开放和关闭时间都很短。 αβ 的平均通道开放概率 (P o) 为 0.54，αβT 的平均通道开放概率 (P o) 为 0.50。相比之下，αγ 和 αγT 通道表现出不同的动力学：αγ 通道（Li+ 中为 6.7 pS）要么具有较长的开放时间和较短的关闭时间，导致较高的 P o (0.78)，要么具有较短的开放时间和较长的关闭时间，导致较低的 P o (0.16)。所有 αγ 通道的平均 P o 为 0.48。 αγT（Li+ 中为 6.6 pS）表现为具有不同动力学的单一通道群体：平均打开时间为 1.2 s，关闭时间为 0.4 s，平均 Po 为 0.6，与 αγ 类似。在移液管溶液中加入 0.1 μM 阿米洛利，可将 αγT 的平均开放时间缩短至 151 ms，而不会显着改变关闭时间。我们还检查了阿米洛利阻断 αβ、αβT（1 μM 阿米洛利）和 αγT（0.1 μM 阿米洛利）通道的动力学。 αβ和αβT具有相似的阻断和解阻断速率常数，而αγT的解阻断速率常数比αβT慢10倍。我们的结果表明 ENaC 的亚基组成是 Po 的主要决定因素。此外，β亚基中羧基末端的删除不会改变通道动力学和P o ，而γ亚基中的类似删除会影响通道动力学，但不会影响P o 。
We have further characterized at the single channel level the properties of epithelial sodium channels formed by coexpression of α with either wild-type β or γ subunits and α with carboxy-terminal truncated β (βT) or γ (γT) subunits in Xenopus laevis oocytes. αβ and αβT channels (9.6 and 8.7 pS, respectively, with 150 mM Li+) were found to be constitutively open. Only upon inclusion of 1 μM amiloride in the pipette solution could channel activity be resolved; both channel types had short open and closed times. Mean channel open probability (P o) for αβ was 0.54 and for αβT was 0.50. In comparison, αγ and αγT channels exhibited different kinetics: αγ channels (6.7 pS in Li+) had either long open times with short closings, resulting in a high P o (0.78), or short openings with long closed times, resulting in a low P o (0.16). The mean P o for all αγ channels was 0.48. αγT (6.6 pS in Li+) behaved as a single population of channels with distinct kinetics: mean open time of 1.2 s and closed time of 0.4 s, with a mean P o of 0.6, similar to that of αγ. Inclusion of 0.1 μM amiloride in the pipette solution reduced the mean open time of αγT to 151 ms without significantly altering the closed time. We also examined the kinetics of amiloride block of αβ, αβT (1 μM amiloride), and αγT (0.1 μM amiloride) channels. αβ and αβT had similar blocking and unblocking rate constants, whereas the unblocking rate constant for αγT was 10-fold slower than αβT. Our results indicate that subunit composition of ENaC is a main determinant of P o. In addition, channel kinetics and P o are not altered by carboxy-terminal deletion in the β subunit, whereas a similar deletion in the γ subunit affects channel kinetics but not P o.
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影响因子：
11.4
作者：
Staub, O;Gautschi, I;Rotin, D
通讯作者：
Rotin, D
DOI：
10.1073/pnas.95.6.3301
发表时间：
1998-03-17
影响因子：
11.1
作者：
Shimkets, RA;Lifton, R;Canessa, CM
通讯作者：
Canessa, CM
影响因子：
64.5
作者：
SHIMKETS, RA;WARNOCK, DG;LIFTON, RP
通讯作者：
LIFTON, RP
DOI：
10.1073/pnas.92.12.5699
发表时间：
1995-06-06
影响因子：
11.1
作者：
SCHILD, L;CANESSA, CM;ROSSIER, BC
通讯作者：
ROSSIER, BC
影响因子：
30.8
作者：
HANSSON, JH;NELSONWILLIAMS, C;LIFTON, RP
通讯作者：
LIFTON, RP