To maintain neutrality, K ions are often accumulated as the counterion.

In general, potassium compounds have excellent water solubility, owing to the high hydration energy of the K ion.

Once the ion channel is activated, K ions flow out of the cell and cause it to hyperpolarize.

This causes the dephosphorylation of the pump, reverting it to its previous conformational state, transporting the K ions into the cell.

The blocking effect is most effective when the K ions flow inward thus at a negative potential.

K ions must give up their water of hydration to pass through the pore.

K ions are octahedrally coordinated in a square bipyramidal geometry by 6 carbonyl bonds from Val.

This leads to a 10,000x selectivity for K ions over Na.

The larger K ion cannot fit through this area.

K ions moving out of the cell bring the membrane potential closer to the equilibrium potential for potassium.