Voltage-gatedion channels (VGICs) are involved in electrical signal transduction and playessential roles in life activities. How membrane potential drivesconformational change at the voltage-sensing domain (S1-S4, VSD) and regulates channel gating is a central themefor voltage-gated ion channels. To elucidate voltage-gating mechanisms, oneneeds to capture VSD structures in both the activated state and resting state.

In recent years, the research team led byProf. GUO Jiangtao from Zhejiang University School ofMedicine has conducted systematic research into the voltage gating mechanism ofTPC1. The latest research results were published in the journal PNAS on November30, and entitled “Voltage-gating and cytosolic Ca²⁺ activation mechanismsof Arabidopsis two-pore channel AtTPC1”.

AtTPC1 belongs tothe VGIC superfamily. It is localized in the vacuolar membrane and is responsiblefor generating slow vacuolar (SV) current. Inaddition to being activated by membrane depolarization, AtTPC1 is also doublyregulated by Ca²⁺. It is activated by cytosolic Ca²⁺ binding at the EF-hand domain but inhibited by vacuolar Ca²⁺ binding at VSDII. Inorder to obtain the structure of AtTPC1 in open-state with the presence of Ca²⁺,based on the previous study, researchers used the mutant AtTPC1ΔCai with threeCa²⁺-coordinating residues on VSDII (D240A/D454A/E528A), which canmitigate the vacuolar Ca²⁺ inhibition.