Single channel properties of human α3 AChRs:: impact of β2, β4 and α5 subunits
Single channel properties of human α3 AChRs:: impact of β2, β4 and α5 subunits
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DOI：
10.1111/j.1469-7793.1999.0657u.x
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发表时间：
1999-05-01
影响因子：
5.5
通讯作者：
Lindstrom, J
中科院分区：
文献类型：
--
作者：
Nelson, ME;Lindstrom, J
1.我们对非洲爪蟾卵母细胞中的人α 3乙酰胆碱受体（AChRs）和来自人神经母细胞瘤细胞系IMR-32的天然AChRs进行了单通道分析。α 3乙酰胆碱受体表现出反映亚基组成的通道特性。α 3 β 2 AChR开放时间分别为0.71 ± 0.14和3.5 ± 0.4 ms，主要电导为26 pS。α 3 β 4 AChR的开放时间为1.4 +/- 0.2和6.5 +/- 0.8 ms，主导电导为31 pS。α 3 β 2的爆发时间为0.82 +/- 0.12和5.3 +/- 0.7 ms，α 3 β 4的爆发时间为1.7 +/- 0.1和16 +/- 1 ms。具有β 2亚基的AChRs的脱敏速度比具有β 4亚基的AChRs快。α 3 α 5 β 2 AChRs的开放时间（5.5 ± 0.3ms）与α 3 β 2 AChRs不同。对于α 3 α 5 β 4 AChRs，额外的电导、开放时间和爆发时间（分别为36 pS、22 +/- 3 ms和43 +/- 4 ms）与α 3 β 4 AChRs不同。α 3 AChR被六甲铵或美加明抑制。六烃季铵阻断α 3 β 4和美加明阻断α 3 β 2的速率常数分别为1.2 x 10（7）和4.6 x 10（7）M-1 s（-1）。5. IMR-32细胞的AChRs具有32 pS的主要电导和1.5 +/- 0.3和9.6 +/- 1.2 ms的开放时间。这些特性与卵母细胞中表达的α 3 β 4 AChRs的特性最为相似。抗体显示，5 +/- 2%的IMR-32 α 3 AChR含有α 5亚基，6 +/- 2%含有β 2亚基。IMR-32 α 3 AChR主要是α 3 β 4 AChR。
1. We performed single channel analysis on human alpha 3 acetylcholine receptors (AChRs) in Xenopus oocytes and native AChRs from the human neuroblastoma cell line IMR-32. alpha 3 AChRs exhibit channel properties that reflect subunit composition.2. alpha 3 beta 2 AChR open times were 0.71 +/- 0.14 and 3.5 +/- 0.4 ms with a predominant conductance of 26 pS. alpha 3 beta 4 AChRs had open times of 1.4 +/- 0.2 and 6.5 +/- 0.8 ms and a predominant conductance of 31 pS. Burst times were 0.82 +/- 0.12 and 5.3 +/- 0.7 ms for alpha 3 beta 2 and 1.7 +/- 0.1 and 16 +/- 1 ms for alpha 3 beta 4. Desensitization was faster for AChRs with the beta 2 subunit than for those with the beta 4 subunit.3. One open time for alpha 3 alpha 5 beta 2 AChRs (5.5 +/- 0 3 ms) was different from those of alpha 3 beta 2 AChRs. For alpha 3 alpha 5 beta 4 AChRs, an additional conductance, open time and burst time (36 pS, 22 +/- 3 ms and 43 +/- 4 ms, respectively) were different from those for alpha 3 beta 4 AChRs.4. alpha 3 AChRs were inhibited by hexamethonium or mecamylamine. The rate constants for block of alpha 3 beta 4 by hexamethonium and of alpha 3 beta 2 by mecamylamine were 1.2 x 10(7) and 4.6 x 10(7) M-1 s(-1), respectively.5. AChRs from IMR-32 cells had a predominant conductance of 32 pS and open times of 1.5 +/- 0.3 and 9.6 +/- 1.2 ms. These properties mere most similar to those of alpha 3 beta 4 AChRs expressed in oocytes. Antibodies revealed that 5 +/- 2% of IMR-32 alpha 3 AChRs contained alpha 5 subunits and 6 +/- 2% contained beta 2 subunits. IMR-32 alpha 3 AChRs are primarily alpha 3 beta 4 AChRs.