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External pH regulates the slowly activating potassium current I sK expressed in Xenopus oocytes
Author(s) -
Yamane Tei-ichi,
Furukawa Tetsushi,
Horikawa Saburo,
Hiraoka Masayasu
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80552-6
Subject(s) - xenopus , biophysics , conductance , potassium , chemistry , potassium channel , membrane potential , biology , biochemistry , physics , gene , organic chemistry , condensed matter physics
A slowly activating, delayed rectifier potassium current, I sK , was expressed in Xenopus laevis oocytes by injection of cRNA transcribed from a rat kidney cDNA clone. External acidification reversibly decreased the current amplitude. The effects were concentration dependent on protons with K d at pH ≈ 5.5 and a Hill coefficient of 1.0. External acidification reduced the maximal conductance ( G max ) without affecting the activation kinetics; this effect was not dependent on membrane voltages. These data suggest that H + ions bind to the channel with a one‐to‐one stoichiometry, and this binding site may be located outside of the membrane electric field.