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. Channels formed by isoform 1 inactivate faster than channels formed by isoform 2. Heterotetramer of potassium channel proteins. Detected in heart, skeletal muscle, brain, and pancreatic islet cells. 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. Produced by alternative initiation at Met-33 of isoform 1. Belongs to the potassium channel family. A (Shaker) (TC 1.A.1.2) subfamily. Kv1.7/KCNA7 sub-subfamily.