What are potassium channels

Potassium channel

English: potassium channel

1 definition

Potassium channels are ion channels in the cell membrane that have a specific conductivity for potassium ions.

2 function

Potassium channels are transmembrane proteins of the cell that form a pore through the cell membrane. The pore is shaped so that it can remove the water molecules from the hydration shell of a potassium ion and take in the dehydrated potassium ions. As the pore continues, the potassium ions are rehydrated. Although the sodium ion is smaller than the potassium ion, it does not come through the potassium channel: the pore cannot remove the water molecules from its hydration shell. The movement of the potassium ions through the channel occurs passively by diffusion.

3 classification

Like other ion channels, potassium channels can be voltage-activated (depending on the membrane potential of the cell) or not voltage-activated. For example, there are potassium channels that open upon a large increase in intracellular calcium ion concentration. Other potassium channels open through compressive or tensile forces acting on the cell membrane.

The voltage activated Potassium channels open when the membrane potential changes. If the membrane potential of a neuron is depolarized, the voltage-activated potassium channels are activated as soon as the threshold potential is exceeded. The voltage-activated sodium channels, however, open faster than the potassium channels. Therefore, the voltage-activated potassium channels are responsible for repolarization during the action potential.

4 forms

There are 4 large groups of potassium channels

In addition, there are mechanosensitive potassium channels that are found in humans in the stereocilia of the inner ear.