Mohapatra Durga P, Siino Dominic F, Trimmer James S
Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, Davis, California 95616, USA.
J Neurosci. 2008 May 7;28(19):4982-94. doi: 10.1523/JNEUROSCI.0186-08.2008.
Voltage-gated potassium (Kv) channels comprise four transmembrane alpha subunits, often associated with cytoplasmic beta subunits that impact channel expression and function. Here, we show that cell surface expression, voltage-dependent activation gating, and phosphorylation-dependent modulation of Kv2.1 are regulated by cytoplasmic N/C interaction within the alpha subunit. Kv2.1 surface expression is greatly reduced by C-terminal truncation. Tailless Kv2.1 channels exhibit altered voltage-dependent gating properties and lack the bulk of the phosphorylation-dependent modulation of channel gating. Remarkably, the soluble C terminus of Kv2.1 associates with tailless channels and rescues their expression, function, and phosphorylation-dependent modulation. Soluble N and C termini of Kv2.1 can also interact directly. We also show that the N/C-terminal interaction in Kv2.1 is governed by a 34 aa motif in the juxtamembrane cytoplasmic C terminus, and a 17 aa motif located in the N terminus at a position equivalent to the beta subunit binding site in other Kv channels. Deletion of either motif disrupts N/C-terminal interaction and surface expression, function, and phosphorylation-dependent modulation of Kv2.1 channels. These findings provide novel insights into intrinsic mechanisms for the regulation of Kv2.1 trafficking, gating, and phosphorylation-dependent modulation through cytoplasmic N/C-terminal interaction, which resembles alpha/beta subunit interaction in other Kv channels.
电压门控钾（Kv）通道由四个跨膜α亚基组成，通常与影响通道表达和功能的胞质β亚基相关联。在此，我们表明Kv2.1的细胞表面表达、电压依赖性激活门控以及磷酸化依赖性调节受α亚基内的胞质N/C相互作用调控。C末端截短会大大降低Kv2.1的表面表达。无尾的Kv2.1通道表现出改变的电压依赖性门控特性，并且缺乏通道门控的大部分磷酸化依赖性调节。值得注意的是，Kv2.1的可溶性C末端与无尾通道结合，并挽救它们的表达、功能以及磷酸化依赖性调节。Kv2.1的可溶性N末端和C末端也可以直接相互作用。我们还表明，Kv2.1中的N/C末端相互作用由近膜胞质C末端的一个34个氨基酸的基序以及位于N末端与其他Kv通道中β亚基结合位点相当位置的一个17个氨基酸的基序控制。删除任何一个基序都会破坏Kv2.1通道的N/C末端相互作用以及表面表达、功能和磷酸化依赖性调节。这些发现为通过胞质N/C末端相互作用调节Kv2.1转运、门控和磷酸化依赖性调节的内在机制提供了新的见解，这种相互作用类似于其他Kv通道中的α/β亚基相互作用。
