Tuluc Petronel, Yarov-Yarovoy Vladimir, Benedetti Bruno, Flucher Bernhard E
Department of Physiology and Medical Physics, Medical University Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria; Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
Department of Physiology and Membrane Biology, UC Davis, Davis, CA 95616, USA.
Structure. 2016 Feb 2;24(2):261-71. doi: 10.1016/j.str.2015.11.011. Epub 2015 Dec 31.
Voltage-gated calcium channels (CaV) regulate numerous vital functions in nerve and muscle cells. To fulfill their diverse functions, the multiple members of the CaV channel family are activated over a wide range of voltages. Voltage sensing in potassium and sodium channels involves the sequential transition of positively charged amino acids across a ring of residues comprising the charge transfer center. In CaV channels, the precise molecular mechanism underlying voltage sensing remains elusive. Here we combined Rosetta structural modeling with site-directed mutagenesis to identify the molecular mechanism responsible for the specific gating properties of two CaV1.1 splice variants. Our data reveal previously unnoticed interactions of S4 arginines with an aspartate (D1196) outside the charge transfer center of the fourth voltage-sensing domain that are regulated by alternative splicing of the S3-S4 linker. These interactions facilitate the final transition into the activated state and critically determine the voltage sensitivity and current amplitude of these CaV channels.
电压门控钙通道（CaV）调节神经和肌肉细胞中的众多重要功能。为了履行其多样的功能，CaV通道家族的多个成员在很宽的电压范围内被激活。钾通道和钠通道中的电压传感涉及带正电荷的氨基酸跨包含电荷转移中心的一圈残基的顺序转变。在CaV通道中，电压传感背后的确切分子机制仍然难以捉摸。在这里，我们将Rosetta结构建模与定点诱变相结合，以确定负责两种CaV1.1剪接变体特定门控特性的分子机制。我们的数据揭示了S4精氨酸与第四电压传感结构域电荷转移中心外的天冬氨酸（D1196）之间以前未被注意到的相互作用，这些相互作用受S3-S4连接体的可变剪接调控。这些相互作用促进最终转变为激活状态，并严格决定这些CaV通道的电压敏感性和电流幅度。
