酸敏感离子通道1a（ASIC1a）是参与突触传递的质子门控通道，疼痛信号，和几种缺血相关的病理状况。蜘蛛毒液衍生的肽PcTx1和Hi1a是已知的两种最有效的ASIC1a抑制剂，有助于促进我们对结构的理解。函数,和ASICs的生物学作用。迄今为止,在ASIC1a具有不同药理学谱的同源蜘蛛肽尚未被发现。在这里，我们报告Hc3a的表征，来自澳大利亚漏斗网蜘蛛Hadronychecerberea的单一抑制剂胱氨酸结肽，与PcTx1序列相似。我们表明Hc3a具有复杂的药理学，并结合不同的ASIC1a构象状态(封闭，打开,并脱敏)具有不同的亲和力，对脱敏作用最显著。Hc3a减缓了质子激活的ASIC1a电流在多个应用pH值之间的脱敏动力学，当与脱敏构象的ASIC1a直接结合时，会促进电流抑制。解析了Hc3a的溶液结构，以及通过诱变研究检查的肽-通道相互作用，以强调Hc3a和PcTx1之间的小序列差异如何导致具有不同药理学的肽。Hc3a的发现扩展了靶向ASIC1a的蜘蛛毒液肽的药理学多样性，并增加了化合物的工具箱，以研究ASIC1门控的复杂性。
Acid-sensing ion channel 1a (ASIC1a) is a proton-gated channel involved in synaptic transmission, pain signalling, and several ischemia-associated pathological conditions. The spider venom-derived peptides PcTx1 and Hi1a are two of the most potent ASIC1a inhibitors known and have been instrumental in furthering our understanding of the structure, function, and biological roles of ASICs. To date, homologous spider peptides with different pharmacological profiles at ASIC1a have yet to be discovered. Here we report the characterisation of Hc3a, a single inhibitor cystine knot peptide from the Australian funnel-web spider Hadronyche cerberea with sequence similarity to PcTx1. We show that Hc3a has complex pharmacology and binds different ASIC1a conformational states (closed, open, and desensitised) with different affinities, with the most prominent effect on desensitisation. Hc3a slows the desensitisation kinetics of proton-activated ASIC1a currents across multiple application pHs, and when bound directly to ASIC1a in the desensitised conformation promotes current inhibition. The solution structure of Hc3a was solved, and the peptide-channel interaction examined via mutagenesis studies to highlight how small differences in sequence between Hc3a and PcTx1 can lead to peptides with distinct pharmacology. The discovery of Hc3a expands the pharmacological diversity of spider venom peptides targeting ASIC1a and adds to the toolbox of compounds to study the intricacies of ASIC1 gating.
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