A human intermediate conductance calcium-activated potassium channel
A human intermediate conductance calcium-activated potassium channel
复制标题
DOI：
10.1073/pnas.94.21.11651
复制
发表时间：
1997-10-14
影响因子：
11.1
通讯作者：
Maylie, J
中科院分区：
文献类型：
--
作者：
Ishii, TM;Silvia, C;Maylie, J
从人胰腺中克隆了一个中电导钙激活钾通道hIK 1。预测的氨基酸序列与小电导钙激活钾通道亚家族相关，但不同，该亚家族保守性约为50%。hIK 1 mRNA在外周组织中检测到，而在脑组织中未检测到。hIK 1在非洲爪蟾卵母细胞的表达引起内向整流钾电流，这是激活亚微摩尔浓度的细胞内钙（K-0.5 = 0.3 μ M）。尽管钙的K-0.5与小电导钙激活钾通道的K-0.5相似，但从Hill方程推导出的斜率因子显着降低（1.7与3.5）。单通道电流振幅反映了宏观向内整流，并揭示了在向内方向的电导水平为39 pS。hIK 1电流被Charybdotoxin（Ki = 2.5 nM）和克霉唑（Ki = 24.8 nM）可逆性阻断，但被蜂毒肽（100 nM）、伊比利亚毒素（50 nM）或酮康唑（10 μ M）影响最小。这些生物物理和药理学特性与天然中间电导钙激活钾通道（包括红细胞Gardos通道）一致。
An intermediate conductance calcium-activated potassium channel, hIK1, was cloned from human pancreas. The predicted amino acid sequence is related to, but distinct from, the small conductance calcium-activated potassium channel subfamily, which is approximate to 50% conserved. hIK1 mRNA was detected in peripheral tissues but not in brain. Expression of hIK1 in Xenopus oocytes gave rise to inwardly rectifying potassium currents, which were activated by submicromolar concentrations of intracellular calcium (K-0.5 = 0.3 mu M). Although the K-0.5 for calcium was similar to that of small conductance calcium-activated potassium channels, the slope factor derived from the Hill equation was significantly reduced (1.7 vs. 3.5). Single-channel current amplitudes reflected the macroscopic inward rectification and revealed a conductance level of 39 pS in the inward direction. hIK1 currents were reversibly blocked by charybdotoxin (K-i = 2.5 nM) and clotrimazole (K-i = 24.8 nM) but were minimally affected by apamin (100 nM), iberiotoxin (50 nM), or ketoconazole (10 mu M). These biophysical and pharmacological properties are consistent with native intermediate conductance calcium-activated potassium channels, including the erythrocyte Gardos channel.