Voltage-sensitive phosphatases (VSPs) are unique enzymes that mediate electrochemical coupling by convertingphosphoinositides in response to membrane depolarization. In mammals, VSPs are involved in regulatingsperm motility. The basic functionality of mammalian VSPs has remained enigmatic, as retention tointracellular compartments precluded functional analysis. Here, a membrane yeast two-hybrid assay identifiesbasigin as an accessory subunit of mouse VSP (mVSP). Co-expression with basigin or its homologsinduced trafficking of mVSP from the endoplasmic reticulum to the plasma membrane. Mutational analysisand structural predictions by AlphaFold-Multimer showed that the functional effect on mVSP requires interactionof the transmembrane region of basigin with the voltage sensor domain of mVSP. Basigin-mediatedsurface localization allowed for functional analysis, revealing that mVSP acts as a voltage-activated5-phosphatase against PI(4,5)P 2 and PI(3,4,5)P 3 with a more negative activation range compared to nonmammalianVSPs.
Shaikh et al. (Wed,) studied this question.