Calcium-dependent block of P2X7 receptor channel function is allosteric.
Calcium-dependent block of P2X7 receptor channel function is allosteric.
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DOI：
10.1085/jgp.201110647
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发表时间：
2011-10
期刊：
影响因子：
--
通讯作者：
Stojilkovic SS
中科院分区：
文献类型：
--
作者：
Yan Z;Khadra A;Sherman A;Stojilkovic SS
在嘌呤能P2 X受体（P2 XR）通道中，P2 X7 R表现出最复杂的门控动力学;正构激动剂在胞外域的结合诱导受体复合物的构象变化，其有利于从关闭状态到打开和扩张状态的门控转变。Bath Ca 2+通过一种尚未表征的机制影响P2 X7 R门控：它可以通过降低三磷酸腺苷4 −（ATP 4 −）浓度（一种被认为是P2 X7 R正构激动剂的形式），作为变构调节剂，和/或直接改变孔对阳离子的选择性来发挥作用。在这项研究中，我们结合生物物理和数学方法来阐明钙在P2 X7 R门控中的作用。在幼稚受体，浴钙影响的激活渗透性动力学间接降低正构激动剂的效力，以浓度依赖性的方式和独立的浓度的游离酸形式的激动剂和状态的泛连接蛋白-1（Panx 1）通道。浴钙也促进了受体失活率的浓度依赖性的方式，但不影响受体失活的渐进性延迟所造成的重复激动剂的应用。钙对受体失活动力学的影响是快速和可逆的。A438079是一种有效的正构竞争性拮抗剂，在洗脱期内保护2 ′（3′）-O-4-苯甲酰苯甲酰基）ATP对电流衰减动力学的再结合作用，但在A438079存在下，钙也增加了受体失活的速率。相应的动力学（马尔可夫状态）模型表明，结合亲和力的降低导致电流幅度的降低和受体失活的促进，两者都以细胞外钙浓度依赖性的方式表示为希尔函数。结果表明，在生理浓度的钙作为一个负变构调节剂的P2 X7 R通过降低受体的亲和力正构配体激动剂，但不是拮抗剂，而不是通过直接或间接影响渗透性动力学通过Panx 1通道。我们希望这些结果可以推广到其他P2 XR。
Among purinergic P2X receptor (P2XR) channels, the P2X7R exhibits the most complex gating kinetics; the binding of orthosteric agonists at the ectodomain induces a conformational change in the receptor complex that favors a gating transition from closed to open and dilated states. Bath Ca2+ affects P2X7R gating through a still uncharacterized mechanism: it could act by reducing the adenosine triphosphate4− (ATP4−) concentration (a form proposed to be the P2X7R orthosteric agonist), as an allosteric modulator, and/or by directly altering the selectivity of pore to cations. In this study, we combined biophysical and mathematical approaches to clarify the role of calcium in P2X7R gating. In naive receptors, bath calcium affected the activation permeability dynamics indirectly by decreasing the potency of orthosteric agonists in a concentration-dependent manner and independently of the concentrations of the free acid form of agonists and status of pannexin-1 (Panx1) channels. Bath calcium also facilitated the rates of receptor deactivation in a concentration-dependent manner but did not affect a progressive delay in receptor deactivation caused by repetitive agonist application. The effects of calcium on the kinetics of receptor deactivation were rapid and reversible. A438079, a potent orthosteric competitive antagonist, protected the rebinding effect of 2’(3′)-O-4-benzoylbenzoyl)ATP on the kinetics of current decay during the washout period, but in the presence of A438079, calcium also increased the rate of receptor deactivation. The corresponding kinetic (Markov state) model indicated that the decrease in binding affinity leads to a decrease in current amplitudes and facilitation of receptor deactivation, both in an extracellular calcium concentration–dependent manner expressed as a Hill function. The results indicate that calcium in physiological concentrations acts as a negative allosteric modulator of P2X7R by decreasing the affinity of receptors for orthosteric ligand agonists, but not antagonists, and not by affecting the permeability dynamics directly or indirectly through Panx1 channels. We expect these results to generalize to other P2XRs.
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DOI：
10.1016/j.bbrc.2008.10.042
发表时间：
2008-12-19
影响因子：
3.1
作者：
Nicke, Annette
通讯作者：
Nicke, Annette
影响因子：
5.3
作者：
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通讯作者：
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影响因子：
5.5
作者：
Dubyak, George R.
通讯作者：
Dubyak, George R.
影响因子：
5.5
作者：
Klapperstück, M;Büttner, C;Markwardt, F
通讯作者：
Markwardt, F
影响因子：
5.5
作者：
COCKCROFT, S;GOMPERTS, BD
通讯作者：
GOMPERTS, BD