The following metal ion activates many enzymes, participates in the...

Potassium metal ion activates many enzymes, participates in the oxidation of glucose to produce $ATP$ and with $Na$, is responsible for the transmission of nerve signals.

Potassium is the main intracellular ion for all types of cells, while having a major role in maintenance of fluid and electrolyte balance. Animals, in particular, employ sodium and potassium differentially to generate electrical potentials in animal cells, especially in nervous tissue.