Structure：测定钙通道的相互作用热点区域

电压门控性钙通道 (CaVs) 是由多个亚基组成的大的复合体，控制钙进入细胞。而电压门控性钙通道的致孔剂(CaVα1)和细胞质亚基(CaVβ)间的相互作用，是通过CaVα1的α交互作用区 (AID) 和CaVβ的α结合口袋 (ABP) 的高亲和力进行的。

在最新研究中，Van Petegem等人采用等温滴定量热法分析AID-ABP相互作用的热动力学。结果发现，AID-ABP作用的热动力学结果与其氨基酸排列顺序一样具有非常高的相似度，所有CaV1和CaV2的AID肽几乎是以相同的纳摩尔浓度与CAVβ亲和。

尽管AID-ABP相互作用的界面包含24个侧链，但Van Petegem等进行的丙氨酸扫描诱变实验却显示，结合能集中在包括四个高度保守残基的两个互为补充的热点区域。另外，电生理实验表明，如果阻断热点区域的交互作用，则CaVβ会阻止CaV1.2的通行和调节功能。

总之，所有的研究数据证实，CaVα1-CaVβ相互作用的关键是AID-ABP的作用界面，热点区域决定着这些蛋白质相互作用的亲和力。这项研究结果揭示了蛋白质通过阻断CaVα1-CaVβ复合体的形成来控制细胞的兴奋性毒性的调节机制。

相关论文发表在2008年2月12日的《结构》（Structure）杂志上。（科学网武彦文/编译）

生物谷推荐原始出处：

（Structure），Vol 16, 280-294, 12 February 2008，Filip Van Petegem, Daniel L. Minor Jr.

Alanine-Scanning Mutagenesis Defines a Conserved Energetic Hotspot in the CaVα1 AID-CaVβ Interaction Site that Is Critical for Channel Modulation

Filip Van Petegem, Karl E. Duderstadt, Kimberly A. Clark, Michelle Wang, and Daniel

Summary

Voltage-gated calcium channels (CaVs) are large, multisubunit complexes that control cellular calcium entry. CaV pore-forming (CaVα1) and cytoplasmic (CaVβ) subunits associate through a high-affinity interaction between the CaVα1 α interaction domain (AID) and CaVβ α binding pocket (ABP). Here we analyze AID-ABP interaction thermodynamics using isothermal titration calorimetry. We find that commensurate with their strong sequence similarity, all CaV1 and CaV2 AID peptides bind CaVβ with similar nanomolar affinities. Although the AID-ABP interface encompasses 24 side chains, alanine-scanning mutagenesis reveals that the binding energy is focused in two complementary hotspots comprising four deeply conserved residues. Electrophysiological experiments show that hotspot interaction disruption prevents trafficking and functional modulation of CaV1.2 by CaVβ. Together, the data support the primacy of the AID-ABP interface for CaVα1-CaVβ association, underscore the idea that hotspots dominate protein-protein interaction affinities, and uncover a target for strategies to control cellular excitability by blocking CaVα1-CaVβ complex formation.