Rhodes K J, Monaghan M M, Barrezueta N X, Nawoschik S, Bekele-Arcuri Z, Matos M F, Nakahira K, Schechter L E, Trimmer J S
CNS Disorders, Wyeth-Ayerst Research, Princeton, New Jersey 08543, USA.
J Neurosci. 1996 Aug 15;16(16):4846-60. doi: 10.1523/JNEUROSCI.16-16-04846.1996.
Recent cloning of K+ channel beta subunits revealed that these cytoplasmic polypeptides can dramatically alter the kinetics of current inactivation and promote efficient glycosylation and surface expression of the channel-forming alpha subunits. Here, we examined the expression, distribution, and association of two of these beta subunits, Kv beta 1 and Kv beta 2, in adult rat brain. In situ hybridization using cRNA probes revealed that these beta-subunit genes are heterogeneously expressed, with high densities of Kv beta 1 mRNA in the striatum, CA1 subfield of the hippocampus, and cerebellar Purkinje cells, and high densities of Kv beta 2 mRNA in the cerebral cortex, cerebellum, and brainstem. Immunohistochemical staining using subunit-specific monoclonal and affinity-purified polyclonal antibodies revealed that the Kv beta 1 and Kv beta 2 polypeptides frequently co-localize and are concentrated in neuronal perikarya, dendrites, and terminal fields, and in the juxtaparanodal region of myelinated axons. Immunoblot and reciprocal co-immunoprecipitation analyses indicated that Kv beta 2 is the major beta subunit present in rat brain membranes, and that most K+ channel complexes containing Kv beta 1 also contain Kv beta 2. Taken together, these data suggest that Kv beta 2 is a component of almost all K+ channel complexes containing Kv 1 alpha subunits, and that individual channels may contain two or more biochemically and functionally distinct beta-subunit polypeptides.
最近对钾离子通道β亚基的克隆研究表明，这些胞质多肽能够显著改变电流失活的动力学，并促进形成通道的α亚基的有效糖基化和表面表达。在此，我们研究了成年大鼠脑中这两种β亚基，即Kvβ1和Kvβ2的表达、分布及相互关系。使用cRNA探针进行原位杂交显示，这些β亚基基因呈异质性表达，在纹状体、海马体CA1亚区和小脑浦肯野细胞中Kvβ1 mRNA密度较高，而在大脑皮层、小脑和脑干中Kvβ2 mRNA密度较高。使用亚基特异性单克隆抗体和亲和纯化的多克隆抗体进行免疫组织化学染色显示，Kvβ1和Kvβ2多肽经常共定位，并集中在神经元胞体、树突和终末区域，以及有髓轴突的旁结区。免疫印迹和相互免疫共沉淀分析表明，Kvβ2是大鼠脑膜中主要的β亚基，并且大多数含有Kvβ1的钾离子通道复合物也含有Kvβ2。综上所述，这些数据表明Kvβ2是几乎所有含有Kv1α亚基的钾离子通道复合物的一个组成部分，并且单个通道可能包含两种或更多种在生化和功能上不同的β亚基多肽。
