This protein mediates the voltage-dependent potassium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a potassium-selective channel through which potassium ions may pass in accordance with their electrochemical gradient (By similarity). Homotetramer (Probable). Heterotetramer of potassium channel proteins (By similarity). The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. The tail may be important in modulation of channel activity and/or targeting of the channel to specific subcellular compartments. Phosphorylation of serine residues in the inactivation gate inhibits rapid channel closure. Belongs to the potassium channel family. C (Shaw) (TC 1.A.1.2) subfamily. Kv3.4/KCNC4 sub-subfamily.