Na+ block and permeation in a K+ channel of known structure.
The effects of intracellular Na(+) were studied on K(+) and Rb(+) currents through single KcsA channels. At low voltage, Na(+) produces voltage-dependent block, which becomes relieved at high voltage by a "punchthrough" mechanism representing Na(+) escaping from its blocking site through the selectivity filter. The Na(+) blocking site is located in the wide, hydrated vestibule, and it displays unexpected selectivity for K(+) and Rb(+) against Na(+). The voltage dependence of Na(+) block reflects coordinated movements of the blocker with permeant ions in the selectivity filter.
Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454, USA.
Crina M
CM
Nimigean
Christopher
C
Miller
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008051:Lipid Bilayers / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008567:Membranes, Artificial; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology
D001426:Bacterial Proteins; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D015221:Potassium Channels; C107790:prokaryotic potassium channel; D012964:Sodium