Electrifying phosphatases.

Ci-VSP, a recently described protein with sequence similarity to both the voltage-sensing domain of a voltage-gated potassium channel and the phosphatase PTEN, functions as a transmembrane phosphoinositide phosphatase that is regulated by changes in voltage across the plasma membrane. Ci-VSP dephosphorylated phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P3] in vitro, exhibited capacitative currents that resembled ion channel gating currents, and, when coexpressed with potassium channels that are regulated by PtdIns(4,5)P2, conferred sensitivity of potassium current amplitude to prolonged changes in membrane potential. How the voltage-sensing (VS) domain of Ci-VSP communicates with the phosphatase domain, and how the VS domain moves its charges across the membrane electric field in the absence of a transmembrane pore domain, remain to be determined.