Potassium voltage-gated channel subfamily H member 3 is a protein that in humans is encoded by the KCNH3 gene. The protein encoded by this gene is a voltage-gated potassium channel subunit. Pore-forming (alpha) subunit of voltage-gated potassium channel. Elicits an outward current with fast inactivation. Channel properties may be modulated by cAMP and subunit assembly. The potassium channel is probably composed of a homo- or heterotetrameric complex of pore-forming alpha subunits that can associate with modulating beta subunits. Detected only in brain, in particular in the telencephalon. Detected in the cerebral cortex, occipital pole, frontal and temporal lobe, putamen, amygdala, hippocampus and caudate nucleus.