TRPC1/4/5 channels are non-specific cation channels implicated in a wide variety of diseases, and TRPC1/4/5 inhibitors have recently entered clinical trials. However, fundamental and translational studies require a better understanding of TRPC1/4/5 channel regulation by endogenous and exogenous factors. Although several potent and selective TRPC1/4/5 modulators have been reported, the paucity of mechanistic insights into their modes-of-action remains a barrier to the development of new chemical probes and drug candidates. Xanthine-based modulators include the most potent and selective TRPC1/4/5 inhibitors described to date, as well as TRPC5 activators. Our previous studies suggest that xanthines interact with a, so far, elusive pocket of TRPC1/4/5 channels that is essential to channel gating. Here we report the structure of a small-molecule-bound TRPC1/4/5 channel—human TRPC5 in complex with the xanthine Pico145—to 3.0 Å. We found that Pico145 binds to a conserved lipid binding site of TRPC5, where it displaces a bound phospholipid. Our findings explain the mode-of-action of xanthine-based TRPC1/4/5 modulators, and suggest a structural basis for TRPC1/4/5 modulation by endogenous factors such as (phospho)lipids and Zn²⁺ ions. These studies lay the foundations for the structure-based design of new generations of TRPC1/4/5 modulators.

TRPC1/4/5 通道是与多种疾病有关的非特异性阳离子通道，TRPC1/4/5 抑制剂最近已进入临床试验阶段。然而，基础和转化研究需要更好地了解内源性和外源性因素对 TRPC1/4/5 通道的调节。尽管已经报道了几种有效和选择性的 TRPC1/4/5 调节剂，但缺乏对其作用模式的机理见解仍然是开发新化学探针和候选药物的障碍。基于黄嘌呤的调节剂包括迄今为止描述的最有效和选择性的 TRPC1/4/5 抑制剂，以及 TRPC5 激活剂。我们以前的研究表明，黄嘌呤与迄今为止难以捉摸的 TRPC1/4/5 通道口袋相互作用，这对通道门控至关重要。在这里，我们报告了小分子结合的 TRPC1/4/5 通道的结构——人类 TRPC5 与黄嘌呤 Pico145 的复合物——至 3.0 Å。我们发现 Pico145 与 TRPC5 的保守脂质结合位点结合，在该位点取代结合的磷脂。我们的研究结果解释了基于黄嘌呤的 TRPC1/4/5 调节剂的作用模式，并提出了 TRPC1/4/5 通过内源性因子（如（磷酸）脂质和 Zn 进行调节）的结构基础²⁺离子。这些研究为新一代 TRPC1/4/5 调制器的基于结构的设计奠定了基础。