title: Current and selectivity in a model sodium channel under physiological conditions: Dynamic Monte Carlo simulations.
abstract: A reduced model of a sodium channel is analyzed using Dynamic Monte Carlo simulations. These include the first simulations of ionic current under approximately physiological ionic conditions through a model sodium channel and an analysis of how mutations of the sodium channel's DEKA selectivity filter motif transform the channel from being Na(+) selective to being Ca(2+) selective. Even though the model of the pore, amino acids, and permeant ions is simplified, the model reproduces the fundamental properties of a sodium channel (e.g., 10 to 1 Na(+) over K(+) selectivity, Ca(2+) exclusion, and Ca(2+) selectivity after several point mutations). In this model pore, ions move through the pore one at a time by simple diffusion and Na(+) versus K(+) selectivity is due to both the larger K(+) not fitting well into the selectivity filter that contains amino acid terminal groups and K(+) moving more slowly (compared to Na(+)) when it is in the selectivity filter.
authors.affiliation: Department of Physical Chemistry, University of Pannonia, Veszprém, Hungary.
authors.forename: Eva
authors.initials: E
authors.lastname: Csányi
authors.forename: Dezso
authors.initials: D
authors.lastname: Boda
authors.forename: Dirk
authors.initials: D
authors.lastname: Gillespie
authors.forename: Tamás
authors.initials: T
authors.lastname: Kristóf
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D017136:Ion Transport / Q000502:physiology; D008954:Models, Biological; D009010:Monte Carlo Method; D011188:Potassium / Q000737:chemistry / Q000378:metabolism*; D012964:Sodium / Q000737:chemistry / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism*; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D015222:Sodium Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium
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