Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA.
Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 93858-2330, USA; California Institute for Quantitative Biomedical Research, University of California, San Francisco, San Francisco, CA 93858-2330, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 93858-2330, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Neuron. 2019 Mar 20;101(6):1134-1149.e3. doi: 10.1016/j.neuron.2019.01.011. Epub 2019 Feb 4.
Calcium-dependent inactivation (CDI) is a fundamental autoregulatory mechanism in Ca1 and Ca2 voltage-gated calcium channels. Although CDI initiates with the cytoplasmic calcium sensor, how this event causes CDI has been elusive. Here, we show that a conserved selectivity filter (SF) domain II (DII) aspartate is essential for CDI. Mutation of this residue essentially eliminates CDI and leaves key channel biophysical characteristics untouched. DII mutants regain CDI by placing an aspartate at the analogous SF site in DIII or DIV, but not DI, indicating that Ca SF asymmetry is key to CDI. Together, our data establish that the Ca SF is the CDI endpoint. Discovery of this SF CDI gate recasts the Ca inactivation paradigm, placing it squarely in the framework of voltage-gated ion channel (VGIC) superfamily members in which SF-based gating is important. This commonality suggests that SF inactivation is an ancient process arising from the shared VGIC pore architecture.
钙依赖性失活（CDI）是钙 1 和钙 2 电压门控钙通道中的基本自调节机制。尽管 CDI 是由细胞质钙传感器引发的，但这一事件如何导致 CDI 一直难以捉摸。在这里，我们表明保守的选择性滤器（SF）域 II（DII）天冬氨酸对于 CDI 是必不可少的。该残基的突变基本上消除了 CDI，而不会影响关键的通道生物物理特性。通过在 DIII 或 DIV 中的类似 SF 位点放置天冬氨酸，DII 突变体可以恢复 CDI，但不能在 DI 中，这表明 Ca SF 不对称性是 CDI 的关键。总之，我们的数据表明 Ca SF 是 CDI 的终点。该 SF CDI 门的发现重新构建了 Ca 失活范例，将其置于电压门控离子通道（VGIC）超家族成员的框架内，其中 SF 门控很重要。这种共性表明 SF 失活是一种古老的过程，源于共享的 VGIC 孔结构。
