High-conductance calcium-activated potassium channels in rat brain: pharmacology, distribution, and subunit composition.
High-conductance calcium-activated potassium channels in rat brain: pharmacology, distribution, and subunit composition.
复制标题
大鼠脑中高电导钙激活钾通道：药理学、分布和亚基组成。
DOI：
10.1021/bi983040c
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发表时间：
1999
期刊：
影响因子：
2.9
通讯作者：
H. Knaus
中科院分区：
文献类型：
--
作者：
S. Wanner;R. Koch;A. Koschak;M. Trieb;Maria L. Garcia;G. Kaczorowski;H. Knaus
在大鼠脑中，高电导Ca 2+激活的K+（BK）通道靶向轴突和神经末梢[Knaus，H. G.，等人（1996）J. Neurosci. 16，955-963]，但其区域表达和亚基组成的绝对水平尚未完全确定。为了研究这些问题，采用了IbTX类似物（[125 I] IbTX-D19 Y/Y36 F），其以高亲和力（Kd = 21 pM）选择性地结合神经元BK通道。在双功能试剂存在下，[125 I] IbTX-D19 Y/Y36 F的交联实验导致放射性共价掺入表观分子量为25 kDa的蛋白质中。去糖基化和免疫沉淀的研究，提出了对α和平滑肌β亚基的BK通道的抗体表明，β亚基，是与神经元BK通道是一种新的蛋白质。定量受体放射自显影显示BK通道表达的最高水平的外层的新皮层，海马穿通路径的预测，和脚间核。这种分布模式也已在BK通道选择性抗体的免疫细胞化学实验中得到证实。两者合计，这些研究结果意味着，神经元BK通道在大脑中表现出有限的分布，并具有不同于其平滑肌同源物的亚基组成。
In rat brain, high-conductance Ca2+-activated K+ (BK) channels are targeted to axons and nerve terminals [Knaus, H. G., et al. (1996) J. Neurosci. 16, 955-963], but absolute levels of their regional expression and subunit composition have not yet been fully established. To investigate these issues, an IbTX analogue ([125I]IbTX-D19Y/Y36F) was employed that selectively binds to neuronal BK channels with high affinity (Kd = 21 pM). Cross-linking experiments with [125I]IbTX-D19Y/Y36F in the presence of a bifunctional reagent led to covalent incorporation of radioactivity into a protein with an apparent molecular mass of 25 kDa. Deglycosylation and immunoprecipitation studies with antibodies raised against alpha- and smooth muscle beta-subunits of the BK channel suggest that the beta-subunit that is associated with the neuronal BK channel is a novel protein. Quantitative receptor autoradiography reveals the highest levels of BK channel expression in the outer layers of the neocortex, hippocampal perforant path projections, and the interpeduncular nucleus. This distribution pattern has also been confirmed in immunocytochemical experiments with a BK channel-selective antibody. Taken together, these findings imply that neuronal BK channels exhibit a restricted distribution in brain and have a subunit composition different from those of their smooth muscle congeners.