A kinetic model accounting for all salient features of the K+ channel of the squid giant axon, including the rising phase of the ON gating charge and the Cole-Moore effect, is provided. Upon accounting for a significant feature distinguishing K+, Na+ and Ca2+ channels from channel-forming peptides modeled in our previous 2016 BBA paper, the nucleation-and-growth kinetic model developed therein is extended to simulate ON ionic and gating currents of the K+ channel of the squid giant axon at different depolarization potentials by the use of only two free parameters. K+ channel opening is considered to proceed by progressive aggregation of single subunits, while they are moving their gating charge outward under depolarizing conditions within their tetrameric structure; K+ channel closing proceeds in the opposite direction, by repolarization-induced disaggregation of subunits, accompanied by inward movement of their gating charge.
Keywords: Bilayer lipid membranes; Gating charge; Gating current; K(+) subunits; Nucleation and growth; Sigmoidicity.
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