Revisiting the role of Ca2+ in Shaker K+ channel gating.
Shaker K+ channels were expressed in outside-out macropatches excised from Xenopus oocytes, and the effects on gating of removal of extracellular Ca2+ were examined in the complete absence of intracellular divalent cations. Removal of extracellular Ca2+ by perfusion with EDTA-containing solution caused a small negative shift in the channel's voltage-activation curve and led to an increased nonselective leak, but did not otherwise alter or disrupt the channels. The results contradict the proposal that Ca2+ is an essential component required for maintenance of ion selectivity and proper gating of Kv-type K+ channels. The large nonselective leak in Ca2+-free conditions was found to be a patch-seal phenomenon related to F- ion in the recording pipette.
Hong
K H
KH
Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
Armstrong
C M
CM
Miller
C
C
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002412:Cations; D002713:Chlorine / Q000378:metabolism; D004492:Edetic Acid / Q000378:metabolism; D004594:Electrophysiology; D005461:Fluorine / Q000737:chemistry; D007477:Ions; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism; D051637:Shaker Superfamily of Potassium Channels; D014158:Transcription, Genetic; D014981:Xenopus
D002412:Cations; D007477:Ions; D015221:Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; D005461:Fluorine; D002713:Chlorine; D004492:Edetic Acid; D011188:Potassium; D002118:Calcium