KCNN3 forms one of several calcium-activated potassium channels which are activated in a voltage-independent manner and have a relatively small unit conductance and high sensitivity to intracellular calcium. Activation is followed by membrane hyperpolarization. It is thought to regulate neuronal excitability by contributing to the slow component of synaptic afterhyperpolarization. The channel is blocked by apamin. KCCN3 contains an intracellular N and C terminus and 6 highly conserved transmembrane segments. It exists as a heterooligomer composed of 4 channel subunits each of which binds to a calmodulin subunit which regulates the channel activity through calcium-binding. These channels are thought to be potential therapeutic targets for disorders such as sleep apnea or sudden infant death syndrome and for regulating uterine contractions during labor. It was also suggested that KCNN3 may contribute to age-dependent decline in learning and memory and synaptic plasticity. Also it is thought that KCNN3 channel expression in endothelial cells may be a fundamental determinant of vascular tone and blood pressure.