Department of Chemistry, The University of Chicago, Chicago, IL, USA.
Grossman Center for Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA.
Nat Biotechnol. 2024 Jul;42(7):1065-1074. doi: 10.1038/s41587-023-01928-z. Epub 2023 Sep 21.
Cell surface potassium ion (K) channels regulate nutrient transport, cell migration and intercellular communication by controlling K permeability and are thought to be active only at the plasma membrane. Although these channels transit the trans-Golgi network, early and recycling endosomes, whether they are active in these organelles is unknown. Here we describe a pH-correctable, ratiometric reporter for K called pHlicKer, use it to probe the compartment-specific activity of a prototypical voltage-gated K channel, Kv11.1, and show that this cell surface channel is active in organelles. Lumenal K in organelles increased in cells expressing wild-type Kv11.1 channels but not after treatment with current blockers. Mutant Kv11.1 channels, with impaired transport function, failed to increase K levels in recycling endosomes, an effect rescued by pharmacological correction. By providing a way to map the organelle-specific activity of K channels, pHlicKer technology could help identify new organellar K channels or channel modulators with nuanced functions.
细胞膜钾离子 (K) 通道通过控制 K 通透性来调节营养物质运输、细胞迁移和细胞间通讯，被认为仅在质膜上活跃。尽管这些通道通过反式高尔基体网络和早期及再循环内体运输，但它们在这些细胞器中是否活跃尚不清楚。在这里，我们描述了一种称为 pHlicKer 的 pH 可校正的钾离子比率报告器，并用它来探测典型的电压门控钾通道 Kv11.1 的区室特异性活性，并表明这种细胞表面通道在细胞器中是活跃的。在表达野生型 Kv11.1 通道的细胞中，腔室中的 K 增加，但在用电流阻断剂处理后没有增加。具有转运功能受损的突变 Kv11.1 通道无法增加再循环内体中的 K 水平，而通过药理学校正可以挽救这种作用。通过提供一种绘制 K 通道区室特异性活性的方法，pHlicKer 技术可以帮助识别具有细微功能的新的细胞器钾通道或通道调节剂。
