Voltage Gated Channels

1. Voltage Gated Channels By Nick and Becky

2. What Are They? • Voltage-gated ion channels are membrane proteins that enable selected inorganic ions to pass across the cell membrane. • They play a key role in the electrical signalling of neurons.

3. How does it work? • They open and close in response to changes in transmembrane voltage. They play a key role in the electrical signalling of neurons. • When the cell membrane is polarized, so that the interior of the cell is at a negative voltage relative to the exterior, Kv (voltage gated) channels remain closed. When the membrane is depolarized, these channels open rapidly, allowing ions to flow passively down their electrochemical gradients, at near diffusion rates. Kv channels have two principal functions: ion conduction, and voltage sensing. • Corresponding to these two functions, Kv channel subunits contain two distinct, but functionally coupled transmembrane domains. The pore domain is responsible for the ion selectivity and conduction, and also for channel gating per se, whereas the voltage-sensing domain triggers a change in conformation of the pore domain in response to changes in transmembrane voltage.

4. Example • Potassium channels are membrane proteins which allow rapid and selective flow of potassium ions across the cell membrane, which in turn creates signals in cells. • Voltage gated potassium channels open and close when there are changes in the transmembrane potential, when the channels are open they allow a flow of potassium ions from the cell in order to restore the membrane potential.

5. References Image – http://www.nature.com/nature/journal/v444/n7120/fig_tab/nature05408_F1.html Other info – http://scienceweek.com/2005/sw050422-3.htm