Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London WC1E 6BT, UK.
Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6BT, UK.
Cell Rep. 2018 Nov 6;25(6):1610-1621.e5. doi: 10.1016/j.celrep.2018.10.033.
Voltage-gated calcium channel auxiliary α2δ subunits are important for channel trafficking and function. Here, we compare the effects of α2δ-1 and an α2δ-like protein called Cachd1 on neuronal N-type (Ca2.2) channels, which are important in neurotransmission. Previous structural studies show the α2δ-1 VWA domain interacting with the first loop in Ca1.1 domain-I via its metal ion-dependent adhesion site (MIDAS) motif and additional Cache domain interactions. Cachd1 has a disrupted MIDAS motif. However, Cachd1 increases Ca2.2 currents substantially (although less than α2δ-1) and increases Ca2.2 cell surface expression by reducing endocytosis. Although the effects of α2δ-1 are abolished by mutation of Asp122 in Ca2.2 domain-I, which mediates interaction with its VWA domain, the Cachd1 responses are unaffected. Furthermore, Cachd1 co-immunoprecipitates with Ca2.2 and inhibits co-immunoprecipitation of α2δ-1 by Ca2.2. Cachd1 also competes with α2δ-1 for effects on trafficking. Thus, Cachd1 influences both Ca2.2 trafficking and function and can inhibit responses to α2δ-1.
电压门控钙通道辅助α2δ亚基对于通道运输和功能很重要。在这里，我们比较了α2δ-1 和一种称为 Cachd1 的α2δ 样蛋白对神经元 N 型（Ca2.2）通道的影响，Ca2.2 通道在神经传递中很重要。先前的结构研究表明，α2δ-1 的 VWA 结构域通过其金属离子依赖性粘附位点（MIDAS）基序与 Ca1.1 结构域-I 的第一个环相互作用，并与额外的 Cache 结构域相互作用。Cachd1 的 MIDAS 基序被破坏。然而，Cachd1 会通过减少内吞作用来显著增加 Ca2.2 电流（尽管不如α2δ-1）并增加 Ca2.2 的细胞表面表达。尽管 Ca2.2 结构域-I 中 Asp122 的突变会消除 α2δ-1 的作用，该突变介导与 VWA 结构域的相互作用，但 Cachd1 的反应不受影响。此外，Cachd1 与 Ca2.2 共免疫沉淀，并抑制 Ca2.2 对 α2δ-1 的共免疫沉淀。Cachd1 还与α2δ-1 竞争对运输的影响。因此，Cachd1 既影响 Ca2.2 的运输又影响其功能，并可以抑制对 α2δ-1 的反应。
