電壓門控性鈣通道 (CaVs) 是由多個(gè)亞基組成的大的復(fù)合體,，控制鈣進(jìn)入細(xì)胞,。而電壓門控性鈣通道的致孔劑(CaVα1)和細(xì)胞質(zhì)亞基(CaVβ)間的相互作用,，是通過(guò)CaVα1的α交互作用區(qū) (AID) 和CaVβ的α結(jié)合口袋 (ABP) 的高親和力進(jìn)行的,。
在最新研究中,，Van Petegem等人采用等溫滴定量熱法分析AID-ABP相互作用的熱動(dòng)力學(xué),。結(jié)果發(fā)現(xiàn)，AID-ABP作用的熱動(dòng)力學(xué)結(jié)果與其氨基酸排列順序一樣具有非常高的相似度,，所有CaV1和CaV2的AID肽幾乎是以相同的納摩爾濃度與CAVβ親和,。
盡管AID-ABP相互作用的界面包含24個(gè)側(cè)鏈，但Van Petegem等進(jìn)行的丙氨酸掃描誘變實(shí)驗(yàn)卻顯示,，結(jié)合能集中在包括四個(gè)高度保守殘基的兩個(gè)互為補(bǔ)充的熱點(diǎn)區(qū)域,。另外，電生理實(shí)驗(yàn)表明,，如果阻斷熱點(diǎn)區(qū)域的交互作用，則CaVβ會(huì)阻止CaV1.2的通行和調(diào)節(jié)功能,。
總之,，所有的研究數(shù)據(jù)證實(shí),，CaVα1-CaVβ相互作用的關(guān)鍵是AID-ABP的作用界面，熱點(diǎn)區(qū)域決定著這些蛋白質(zhì)相互作用的親和力,。這項(xiàng)研究結(jié)果揭示了蛋白質(zhì)通過(guò)阻斷CaVα1-CaVβ復(fù)合體的形成來(lái)控制細(xì)胞的興奮性毒性的調(diào)節(jié)機(jī)制,。
相關(guān)論文發(fā)表在2008年2月12日的《結(jié)構(gòu)》（Structure）雜志上。（科學(xué)網(wǎng) 武彥文/編譯）
生物谷推薦原始出處：
（Structure）,，Vol 16, 280-294, 12 February 2008,，F(xiàn)ilip 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.
