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. Heterotetramer of potassium channel proteins (By similarity). Binds PDZ domains of DLG1, DLG2 and DLG4. The N-terminus may be important in determining the rate of inactivation of the channel while the tail may play a role in modulation of channel activity and/or targeting of the channel to specific subcellular compartments. The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. N-glycosylation promotes the cell surface expression. Belongs to the potassium channel family. A (Shaker) (TC 1.A.1.2) subfamily. Kv1.3/KCNA3 sub-subfamily.