Inactivation rate constant and the number of inactivation gates

带有1、2或4个通道的大鼠Kv1.4的N型失活球已被调查使用在Xenopus细胞中表达的同源人群。由于Kv1.4中的通道、串联二进制和四进制结构的同源人口。Channels encoded y tandem cDNA Kv1.4-Kv1.4 Δ1-145 and Kv1.4-[Kv1.4Δ1-145]伊伊D23伊D2有两个或只有一个tethered inactivation ball， respectively， whereas Kv1.4 itself encodes channels having四个inactivation balls。Kv1.4-Kv1.4编码通道有四个不激活的球，但两个在环路连接的子单元中。宏观货币不激活的时间常数显著地减少为不激活球的数量，而从Kv1.4，Kv1.4-Kv1.4，Kv1.4-Kv1.4，Kv1.4-Kv1.4 Δ1-145和Kv1.4-[Kv1.4Δ1-145] D23和D2通道未被修改。The ratios of the rate constants of inactivation kyD2 inact kyD2 of Kv1.4-Kv1.4，Kv1.4-Kv1.4 -145 and Kv1.4-[Kv1.4Δ1-145] kyD23 channels to that of Kv1.4 channel were 0.78， 0.65 and 0.4， respectively，while the ratios of the rate constant of recovery k-D2rec-D2 of those channels to that of Kv1. 4 were almost unity。The rate constants ky D2 inact D2 for the channel shaving two and four inactivation balls are smaller than those that would be expected if inactivation balls on each channel are independent，sugggesting some interaction occurs between inactivation balls。在此之前，非激活当前的功能将成为一个通道上的非激活球数量已被消除。

N-type inactivation of rat Kv1.4 channels with one, two or four inactivation balls was investigated using homogenous populations of channels expressed in Xenopus oocytes. For homogenous population of channels, tandem dimeric and tetrameric constructs of Kv1.4 were made. Channels encoded y tandem cDNAs Kv1.4-Kv1.4Δ1-145 and Kv1.4-[Kv1.4Δ1-145]ィイD23ィエD2 have two or only one tethered inactivation ball, respectively, whereas Kv1.4 itself encodes channels having four inactivation balls. Kv1.4-Kv1.4 encodes channels having four inactivation balls but two in the loop connecting the subunits. The time constants for inactivation of macroscopic currents were increased significantly as the number of inactivation balls was decreased, whereas the time constants for recovery from inactivation of Kv1.4, Kv1.4-Kv1.4, Kv1.4-Kv1.4Δ1-145 and Kv1.4-[Kv1.4Δ1-145]ィイD23ィエD2 channels were not modified. The ratios of the rate constants of inactivation kィイD2inactィエD2 of Kv1.4-Kv1.4, Kv1.4-Kv1.4Δ1-145 and Kv1.4-[Kv1.4Δ1-145]ィイD23ィエD2 channels to that of Kv1.4 channel were 0.78, 0.65 and 0.4, respectively, while the ratios of the rate constant of recovery kィイD2recィエD2 of those channels to that of Kv1.4 were almost unity. The rate constants kィイD2inactィエD2 for the channel shaving two and four inactivation balls are smaller than those that would be expected if inactivation balls on each channel are independent, suggesting some interaction occurs between inactivation balls. Furthermore, noninactivating current became apparent as the number of inactivation balls on a channel was decreased.