Rhodes K J, Keilbaugh S A, Barrezueta N X, Lopez K L, Trimmer J S
Department of CNS Biological Research, Lederle Laboratories, American Cyanamid Company, Pearl River, New York 10965, USA.
J Neurosci. 1995 Jul;15(7 Pt 2):5360-71. doi: 10.1523/JNEUROSCI.15-07-05360.1995.
Recent cloning of auxiliary subunits associated with voltage-gated ion channels and their subsequent coexpression with the channel forming alpha-subunits has revealed that the expression level, gating and conductance properties of the expressed channels can be profoundly affected by the presence of an auxiliary subunit polypeptide. In the present study, we raised antibodies against the beta-subunit associated with the bovine dendrotoxin sensitive K(+)-channel complex and used these antibodies to characterize the related beta-subunit polypeptides in rat brain. The anti-beta-subunit antibodies displayed a specific reaction on immunoblots of rat brain membranes with a major 38 kDa polypeptide, and a minor 41 kDa polypeptide, which correspond closely to the predicted sizes of the Kv beta 2 and Kv beta 1 beta-subunit polypeptides, respectively, recently cloned from rat brain. Reciprocal coimmunoprecipitation experiments revealed that the beta-subunit polypeptides are associated with Kv1.2 and Kv1.4, but not Kv2.1, alpha-subunits. Immunohistochemical staining revealed that the beta-subunit polypeptides were widely distributed in adult rat brain. Moreover, the cellular distribution of beta-subunit immunoreactivity corresponded closely with immunoreactivity for Kv1.2, and to a lesser extent Kv1.4, but not with Kv2.1. These results suggest that neuronal mechanisms may exist to direct the selective interaction of K+ channel alpha- and beta-subunit polypeptides, and that the properties of K+ channels in specific subcellular domains may be regulated by the formation of heteromultimeric K+ channel complexes containing specific combinations of alpha- and beta-subunits.
最近对与电压门控离子通道相关的辅助亚基的克隆以及随后它们与形成通道的α亚基的共表达表明，辅助亚基多肽的存在可深刻影响所表达通道的表达水平、门控和电导特性。在本研究中，我们制备了针对与牛树突毒素敏感的K(+)通道复合物相关的β亚基的抗体，并使用这些抗体来鉴定大鼠脑中相关的β亚基多肽。抗β亚基抗体在大鼠脑膜免疫印迹上与一条主要的38 kDa多肽和一条次要的41 kDa多肽发生特异性反应，这两条多肽分别与最近从大鼠脑克隆的Kvβ2和Kvβ1β亚基多肽的预测大小密切对应。相互免疫共沉淀实验表明，β亚基多肽与Kv1.2和Kv1.4的α亚基相关，但与Kv2.1的α亚基无关。免疫组织化学染色显示，β亚基多肽在成年大鼠脑中广泛分布。此外，β亚基免疫反应性的细胞分布与Kv1.2的免疫反应性密切对应，在较小程度上与Kv1.4的免疫反应性对应，但与Kv2.1的免疫反应性不对应。这些结果表明，可能存在神经元机制来指导K+通道α亚基和β亚基多肽的选择性相互作用，并且特定亚细胞结构域中K+通道的特性可能通过形成包含特定α亚基和β亚基组合的异源多聚体K+通道复合物来调节。
