Cloning and expression of the large-conductance Ca(2+)-activated K+ channel from colonic smooth muscle.
Cloning and expression of the large-conductance Ca(2+)-activated K+ channel from colonic smooth muscle.
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DOI：
10.1152/ajpgi.1996.271.4.g629
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发表时间：
1996-10
期刊：
影响因子：
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通讯作者：
F. Vogalis;T. Vincent;I. Qureshi;F. Schmalz;Manus W. Ward;Kenton M. Sanders;B. Horowitz
中科院分区：
文献类型：
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作者：
F. Vogalis;T. Vincent;I. Qureshi;F. Schmalz;Manus W. Ward;Kenton M. Sanders;B. Horowitz
我们克隆了犬结肠平滑肌(cslo-α和cslo-beta)大电导钙激活钾通道(BK通道)的α和β亚基的编码基因。Cslo-α与mslo和dslo的核苷酸序列同源性表明它是这些基因的犬类同源物。蛋白质的羧基末端是物种间差异最大的，我们也在这个区域发现了cslo-α的替代外显子。我们在cslo-α的羧基末端区域发现了一个独特的剪接位点，我们称之为5。Northern分析表明，在所有被测试的犬血管和内脏平滑肌中都有α和β亚基的表达。在非洲爪哇卵母细胞中，α-1和α+β亚基cRNA的单独表达导致了钙离子和电压依赖性的电导。以开放概率(NP0)或归一化电导(G/Cmax)的半最大激活电压(V0.5)的变化来衡量α/β通道的活动，比仅由α-亚基组成的通道对游离[Ca~(2+)]更为敏感。在非洲爪哇卵母细胞膜斑块中表达的α通道和α/β通道均不受蛋白激酶G的调节。
We have cloned cDNAs encoding the alpha- and beta-subunits of a large-conductance Ca(2+)-activated K+ channel (BK channel) from canine colonic smooth muscle (cslo-alpha and cslo-beta). Nucleotide sequence homology of cslo-alpha with mslo and dslo suggests that it is the canine homologue of these genes. The carboxy-terminal end of the protein is the most diverse between species, and we have also found alternative exons in cslo-alpha in this region. We have identified a unique splice site in the carboxy-terminal region of cslo-alpha, which we term site 5. Northern analysis demonstrates expression of both alpha- and beta-subunits in all canine vascular and visceral smooth muscles tested. Expression of alpha-1 alone and alpha + beta-subunit cRNA in Xenopus oocytes results in a Ca(2+)- and voltage-dependent conductance. The activity of alpha/beta-channels, measured as either changes in the voltage of half-maximal activation (V0.5) in open probability (NP0) or in the normalized conductance (G/Cmax), was more sensitive to [Ca2+]free than channels composed of the alpha-subunit alone. Neither alpha- nor alpha/beta-channels expressed in membrane patches of Xenopus oocytes were found to be regulated by protein kinase G.