Co-assembly of N-type Ca2+ and BK channels underlies functional coupling in rat brain
Co-assembly of N-type Ca2+ and BK channels underlies functional coupling in rat brain
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DOI：
10.1242/jcs.03399
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发表时间：
2007-03-15
影响因子：
4
通讯作者：
Marrion, Neil V.
中科院分区：
文献类型：
--
作者：
Loane, David J.;Lima, Pedro A.;Marrion, Neil V.
大电导钙激活钾（BK）通道的激活加速动作电位复极化，并在海马锥体神经元中产生快速后超极化。Ca 2+进入与BK通道激活的快速偶联是发生这种情况所必需的，这可能是由于Ca 2+进入通过N型Ca 2+通道与BK通道激活的鉴定偶联。这种选择性偶联非常迅速，并且对细胞内BAPTA具有抗性，表明这两种通道类型很接近。利用免疫共沉淀技术，我们发现在大鼠脑中N型通道比L型通道（Ca（V）1.2）更丰富地与BK通道相关联。在非神经元细胞系中仅表达N型（Ca（V）2.2）和BK（Slo 27）通道的孔形成α亚基产生了强大的宏观电流并再现了相互作用。Ca（V）2.2/Ca-V β（3）亚基与Slo 27通道的共表达揭示了快速的功能偶联。相比之下，在Ca（V）1.2/Ca-V β（3）和Slo 27通道的共表达中观察到了极其罕见的快速功能偶联的例子。N-型通道阻滞剂ω-芋螺毒素GVIA减慢海马锥体神经元动作电位复极，但L-型通道阻滞剂伊拉地平不减慢动作电位复极。这些数据表明，N型Ca ~（2+）和BK通道之间的选择性功能偶联提供了中枢神经元中BK通道的快速激活。
Activation of large conductance Ca2+-activated potassium (BK) channels hastens action potential repolarisation and generates the fast afterhyperpolarisation in hippocampal pyramidal neurons. A rapid coupling of Ca2+ entry with BK channel activation is necessary for this to occur, which might result from an identified coupling of Ca2+ entry through N-type Ca2+ channels to BK channel activation. This selective coupling was extremely rapid and resistant to intracellular BAPTA, suggesting that the two channel types are close. Using reciprocal co-immunoprecipitation, we found that N-type channels were more abundantly associated with BK channels than L-type channels (Ca(V)1.2) in rat brain. Expression of only the pore-forming alpha-subunits of the N-type (Ca(V)2.2) and BK (Slo27) channels in a non-neuronal cell-line gave robust macroscopic currents and reproduced the interaction. Co-expression of Ca(V)2.2/Ca-V beta(3) subunits with Slo27 channels revealed rapid functional coupling. By contrast, extremely rare examples of rapid functional coupling were observed with co-expression of Ca(V)1.2/Ca-V beta(3) and Slo27 channels. Action potential repolarisation in hippocampal pyramidal neurons was slowed by the N-type channel blocker omega-conotoxin GVIA, but not by the L-type channel blocker isradipine. These data showed that selective functional coupling between N-type Ca2+ and BK channels provided rapid activation of BK channels in central neurons.