Biology: Cell`s on/off switch revealed

Washington: Scientists claim to have made a significant advance in understanding how potassium channels in cells "open" and "close", controlling the body`s electrical currents.

Previous studies identified what potassium channels, which permit the flow of electric currents central to many of the body`s biological processes, look like. However, the way the channels open and close in response to regulatory signals was not known.

Now, an international team, led by Walter and Eliza Hall Institute scientists, has got a fresh insight into the process after their research revealed the on/off switch of the cells.

"Potassium currents are central to many cellular processes, and particularly communication between cells. In the central nervous system, for example, electrical signalling underlies perception and movement; whilst in heart, cardiac contraction relies upon rhythmic ebb-and-flow of potassium.

"The electricity comes from the tiny charge associated with each potassium ion. Just as one would use a light switch to turn electrical current on and off, potassium channels use molecular gates to switch conduction on and off in response to physiological signals.

"However, the nature of the gates and the gating process has remained unclear," Dr Jacqui Gulbis, who led the team, said.
Potassium channels are specialised pores in cell membranes. They have a signature region termed the ion selectivity filter, which is responsible for ensuring that only potassium, and not sodium, permeates the membrane.

The findings have been published in the `Cell` journal.


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