Agonists binding nicotinic receptors elicit specific channel‐opening patterns at αγ and αδ sites
Agonists binding nicotinic receptors elicit specific channel‐opening patterns at αγ and αδ sites
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结合烟碱受体的激动剂在 αγ 和 αδ 位点引发特定的通道开放模式
DOI：
10.1113/jphysiol.2013.267781
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Dudel J
中科院分区：
文献类型：
--
作者：
Stock P;Ljaschenko D;Heckmann M;Dudel J
关键点比较了地棘蛙素（Ebd）、氨甲酰胆碱（CCh）和乙酰胆碱（ACh）诱发的高分辨率膜片钳电流。Ebd在αγ位点的结合亲和力是αδ位点的75倍，而CCh和ACh更倾向于αδ位点，观察到类似的短（τ O 1）、中间（τO2）和长（τO3）开放类型。在低浓度Ebd时，τ O2开放最普遍，结合在αγ位点，而τ O 1开放似乎在αδ位点产生，短（~ 0.75 ms）的开放爆发（τB1）来自αγ位点，长（>10 ms）的开放爆发（τB2）来自双配体受体。爆发的持续时间和爆发内的开放依赖于激动剂。受时间分辨率的限制，爆发内的关闭在3 μs时不变。用α-芋螺毒素M1（CTx）阻断αδ位点消除了τ O 1和τ B2，只留下τ O2和短的τ B1爆发，正如预期的那样。αγ和αδ位点的亲和力不同，但它们对打开通道的贡献仍然是难以捉摸的。我们比较了地棘蛙素（Ebd）、氨甲酰胆碱（CCh）和乙酰胆碱（ACh）诱发的高分辨率膜片钳电流。Ebd在αγ位点的结合亲和力是αδ位点的75倍，而CCh和ACh更喜欢αδ位点。所有三种激动剂均观察到类似的短（τ O 1）、中间（τO2）和长（τO3）型开放。τ O2开放在低浓度下最普遍，结合在αγ位点。相比之下，τ O 1开口似乎是在αδ位置产生的。此外，还出现了两种类型的爆发：平均0.75 ms的短爆发（τB1），应该来自αγ位点，以及持续时间为12-25 ms的长爆发（τB2），来自双配体受体。由于时间分辨率的限制，脉冲串内的闭合在3 μs时是不变的。校正错过的关闭，在ACh的情况下，长爆发内的开放持续170 μs，短爆发内的开放持续约30 μs。用α-芋螺毒素M1（CTx）阻断αδ位点消除了τ O 1和τ B2，只留下τ O2和短的τ B1爆发，正如预期的那样。此外，我们发现当受体仅在αγ位点结合ACh时，会发生脱敏。当CTx应用于“胚胎”小鼠终板，单量子电流上升时间增加，幅度和衰减时间常数减少，正如预期的那样。因此，nAChR的αγ和αδ位点引起特定的通道开放模式。
Key pointsHigh‐resolution patch clamp currents evoked by epibatidine (Ebd), carbamylcholine (CCh) and acetylcholine (ACh) were compared. Ebd binds with 75‐fold higher affinity at αγ than at αδ sites, whereas CCh and ACh prefer αδ sites of nicotinic ACh receptor (nAChR) channels.Similar short (τO1), intermediate (τO2) and long (τO3) types of opening were observed. τO2openings were maximally prevalent at low Ebd concentrations, binding at αγ sites, whereas τO1openings appear to be generated at αδ sites.Short (∼0.75 ms) bursts of openings (τB1) arise from the αγ site, and long (>10 ms) bursts (τB2) arise from double liganded receptors. The duration of bursts and of openings within bursts depended on the agonist.Limited by the temporal resolution, the closings within bursts were invariant at 3 μs.Blocking αδ sites with α‐conotoxin M1 (CTx) eliminated both τO1and τB2and left only τO2and the short τB1bursts, as expected.Abstract‘Embryonic’ muscle‐type nicotinic acetylcholine receptor channels (nAChRs) bind ligands at interfaces of α‐ and γ‐ or δ‐subunits. αγ and αδ sites differ in affinity, but their contributions to opening the channel have remained elusive. We compared high‐resolution patch clamp currents evoked by epibatidine (Ebd), carbamylcholine (CCh) and acetylcholine (ACh). Ebd binds with 75‐fold higher affinity at αγ than at αδ sites, whereas CCh and ACh prefer αδ sites. Similar short (τO1), intermediate (τO2) and long (τO3) types of opening were observed with all three agonists. τO2openings were maximally prevalent at low Ebd concentrations, binding at αγ sites. By contrast, τO1openings appear to be generated at αδ sites. In addition, two types of burst appeared: short bursts of an average of 0.75 ms (τB1) that should arise from the αγ site, and long bursts of 12–25 ms (τB2) in duration arising from double liganded receptors. Limited by the temporal resolution, the closings within bursts were invariant at 3 μs. Corrected for missed closings, in the case of ACh the openings within long bursts lasted 170 μs and those in short bursts about 30 μs. Blocking αδ sites with α‐conotoxin M1 (CTx) eliminated both τO1and τB2and left only τO2and the short τB1bursts, as expected. Furthermore we found desensitization when the receptors bound ACh only at the αγ site. When CTx was applied to ‘embryonic’ mouse endplates, monoquantal current rise times were increased, and amplitude and decay time constants were reduced, as expected. Thus the αγ and αδ sites of nAChRs elicit specific channel‐opening patterns.
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DOI：
10.1073/pnas.90.13.6285
发表时间：
1993-07-01
影响因子：
11.1
作者：
CZAJKOWSKI, C;KAUFMANN, C;KARLIN, A
通讯作者：
KARLIN, A
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DOI：
--
发表时间：
1978
期刊：
Journal of Physiology
影响因子：
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作者：
E. Neher;J. Steinbach
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J. Steinbach
影响因子：
5.6
作者：
Unwin, N
通讯作者：
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DOI：
10.1073/pnas.78.6.3678
发表时间：
1981
影响因子：
11.1
作者：
Kistler,J;Stroud,RM
通讯作者：
Stroud,RM
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DOI：
--
发表时间：
1987
期刊：
The Journal of pharmacology and experimental therapeutics
影响因子：
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作者：
Swanson,KL;Albuquerque,EX
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Albuquerque,EX