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Updated: Sep 7, 2025

Introduction to Solid Supported Membrane Based Electrophysiology
Published on: May 11, 2013
Interaction between S4 and the phosphatase domain mediates electrochemical coupling in voltage-sensing phosphatase
Natsuki Mizutani1, Akira Kawanabe1, Yuka Jinno1
1Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
Abstract:
Voltage-sensing phosphatase (VSP) consists of a voltage sensor domain (VSD) and a cytoplasmic catalytic region (CCR), which is similar to phosphatase and tensin homolog (PTEN). How the VSD regulates the innate enzyme component of VSP remains unclear. Here, we took a combined approach that entailed the use of electrophysiology, fluorometry, and structural modeling to study the electrochemical coupling in Ciona intestinalis VSP. We found that two hydrophobic residues at the lowest part of S4 play an essential role in the later transition of VSD-CCR coupling. Voltage clamp fluorometry and disulfide bond locking indicated that S4 and its neighboring linker move as one helix (S4-linker helix) and approach the hydrophobic spine in the CCR, a structure located near the cell membrane and also conserved in PTEN. We propose that the hydrophobic spine operates as a hub for translating an electrical signal into a chemical one in VSP.
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