Mathematics reveals inner workings of potassiu...( evealed that each of the fourproteins ...)

One part of the channel, lying close to the outside of the cell membrane, acts as a filter, allowing only potassium ions into the channel. Four of the a -helices meet in the center of the pore and point toward a cavity capable of holding a potassium ion and about 50 water molecules.

In their current study, MacKinnon and Roux's mathematical analysis showed that the local electrical forces associated with the four helices and the water molecules create an environment more like the inside or outside of the cell than the typical center of a cell membrane. This allows potassium to move quickly through the otherwise unfavorable environment of the cell membrane.

"What this organization does is kind of level the energy mountain separating the inside and outside of the cell. This is a very beautiful design that nature has developed," said MacKinnon.

Though this research is "as basic as it gets," MacKinnon noted that understanding the way the potassium channel functions may play an important role in the development of drugs to deal with diseases ranging from diabetes to heart problems. He said that improved understanding of the channel's structure may allow researchers to design medications that can restore the channel's proper functioning should it go awry.

"If we can properly tune potassium channels, we could, for example, develop new ways of affecting airway smooth muscle, which might have implications for asthma," said MacKinnon.

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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
2-Jul-1999