Atypical mechanism of conduction in potassium channels

作者：Furini Simone; Domene Carmen^*

来源：Proceedings of the National Academy of Sciences, 2009, 106(38): 16074-16077.

DOI：10.1073/pnas.0903226106

• ion translocation
• molecular dynamics simulations
• potential of mean force
• K( ) channels
• umbrella sampling

Potassium channels can conduct passively K( ) ions with rates of up to approximate to 10(8) ions per second at physiological conditions, and they are selective to these species by a factor of 10(4) over Na( ) ions. Ion conduction has been proposed to involve transitions between 2 main states, with 2 or 3 K( ) ions occupying the selectivity filter separated by an intervening water molecule. The largest free energy barrier of such a process was reported to be of the order of 2-3 kcal mol(-1). Here, we present an alternative mechanism for conduction of K( ) in potassium channels where site vacancies are involved, and we propose that coexistence of several ion permeation mechanisms is energetically possible. Conduction can be described as a more anarchic phenomenon than previously characterized by the concerted translocations of K( )-water-K( ).

• 出版日期2009-9-22