Please cite as Berridge, M.J. (2011) Cell Signalling Biology; doi:10.1042/csb0001003
Functional organization of Ca2+-sensitive K+ channels.
Module 3: Figure K+ channel organization (animated)
The closed channel (shown on the left) opens in response to membrane depolarization and/or an increase in internal Ca2+
to allow K+
to flow out of the cell at a rate of 108
ions/s. Depolarization is detected by a voltage sensor that opens the pore through an electromechanical coupling process. Ca2+
acts through binding sites located on a region called the regulator of K+
conductance to open the pore through a chemomechanical coupling process. Once these activation processes open the gated pore, K+
enters the central cavity where it gains access to the selectivity filter. The latter provides a K+
-specific filter, which allows K+
to pass through with a high degree of selectivity. As K+
ions (red dots) pass through the filter, they lose their water of hydration (green dots).