calcium-activated potassium channel activity intermediate conductance calcium-activated potassium channel activity IK KCa channels IK calcium-activated potassium channel activity GO:0022894 Enables the transmembrane transfer of potassium by a channel with a unit conductance of 20 to 85 picoSiemens that opens in response to stimulus by internal calcium ions. Intermediate conductance calcium-activated potassium channels are more sensitive to calcium than are large conductance calcium-activated potassium channels. Transport by a channel involves catalysis of facilitated diffusion of a solute (by an energy-independent process) involving passage through a transmembrane aqueous pore or channel, without evidence for a carrier-mediated mechanism. intermediate conductance KCa channels molecular_function