Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada.
J Gen Physiol. 2020 Jul 6;152(7). doi: 10.1085/jgp.201912524.
The voltage-gated potassium channel Kv1.2 plays a pivotal role in neuronal excitability and is regulated by a variety of known and unknown extrinsic factors. The canonical accessory subunit of Kv1.2, Kvβ, promotes N-type inactivation and cell surface expression of the channel. We recently reported that a neutral amino acid transporter, Slc7a5, alters the function and expression of Kv1.2. In the current study, we investigated the effects of Slc7a5 on Kv1.2 in the presence of Kvβ1.2 subunits. We observed that Slc7a5-induced suppression of Kv1.2 current and protein expression was attenuated with cotransfection of Kvβ1.2. However, gating effects mediated by Slc7a5, including disinhibition and a hyperpolarizing shift in channel activation, were observed together with Kvβ-mediated inactivation, indicating convergent regulation of Kv1.2 by both regulatory proteins. Slc7a5 influenced several properties of Kvβ-induced inactivation of Kv1.2, including accelerated inactivation, a hyperpolarizing shift and greater extent of steady-state inactivation, and delayed recovery from inactivation. These modified inactivation properties were also apparent in altered deactivation of the Kv1.2/Kvβ/Slc7a5 channel complex. Taken together, these findings illustrate a functional interaction arising from simultaneous regulation of Kv1.2 by Kvβ and Slc7a5, leading to powerful effects on Kv1.2 expression, gating, and overall channel function.
电压门控钾通道 Kv1.2 在神经元兴奋性中起着关键作用，并且受到多种已知和未知的外在因素的调节。Kv1.2 的经典辅助亚基 Kvβ促进了通道的 N 型失活和细胞表面表达。我们最近报道了一种中性氨基酸转运蛋白 Slc7a5 改变了 Kv1.2 的功能和表达。在本研究中，我们在存在 Kvβ1.2 亚基的情况下研究了 Slc7a5 对 Kv1.2 的影响。我们观察到 Slc7a5 诱导的 Kv1.2 电流和蛋白表达的抑制作用在共转染 Kvβ1.2 时减弱。然而，Slc7a5 介导的门控效应，包括失活的解除和通道激活的超极化漂移，与 Kvβ介导的失活一起观察到，表明这两种调节蛋白对 Kv1.2 的调节作用是收敛的。Slc7a5 影响 Kvβ诱导的 Kv1.2 失活的几个特性，包括失活加速、超极化漂移和稳态失活程度增加以及失活后恢复的延迟。这些失活特性的改变也在 Kv1.2/Kvβ/Slc7a5 通道复合物的去激活中表现出来。总之，这些发现说明了 Kvβ和 Slc7a5 同时调节 Kv1.2 所产生的功能相互作用，导致对 Kv1.2 的表达、门控和整体通道功能产生强大的影响。
