Probing the cavity of the slow inactivated conformation of shaker potassium channels.
Slow inactivation involves a local rearrangement of the outer mouth of voltage-gated potassium channels, but nothing is known regarding rearrangements in the cavity between the activation gate and the selectivity filter. We now report that the cavity undergoes a conformational change in the slow-inactivated state. This change is manifest as altered accessibility of residues facing the aqueous cavity and as a marked decrease in the affinity of tetraethylammonium for its internal binding site. These findings have implications for global alterations of the channel during slow inactivation and putative coupling between activation and slow-inactivation gates.
Panyi
Gyorgy
G
Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary. cjd@mail.med.upenn.edu
Deutsch
Carol
C
D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D015640:Ion Channel Gating; D007700:Kinetics; D008564:Membrane Potentials; D008954:Models, Biological; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000378:metabolism; D011487:Protein Conformation; D051637:Shaker Superfamily of Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019789:Tetraethylammonium / Q000378:metabolism; D014162:Transfection
D026902:Potassium Channel Blockers; D051637:Shaker Superfamily of Potassium Channels; D002104:Cadmium; D019789:Tetraethylammonium; D011188:Potassium