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.
Horn
Richard
R
Department of Physiology, Institute of Hyperexcitability, Jefferson Medical College, 1020 Locust Street, Philadelphia, PA 19107, USA. richard.horn@jefferson.edu
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001120:Arginine / Q000737:chemistry; D002938:Ciona intestinalis / Q000502:physiology; D019143:Evolution, Molecular; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000737:chemistry / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D010716:Phosphatidylinositols / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D051637:Shaker Superfamily of Potassium Channels / Q000737:chemistry; D013082:Sperm Tail / Q000378:metabolism; D014982:Xenopus laevis
D007473:Ion Channels; D010716:Phosphatidylinositols; D011993:Recombinant Fusion Proteins; D051637:Shaker Superfamily of Potassium Channels; D001120:Arginine; C509671:voltage-sensor-containing phosphatase, Ciona intestinalis; D010744:Phosphoric Monoester Hydrolases