Potassium channel activated by both membrane depolarization or increase in cytosolic Ca(2+) that mediates export of K(+) (PubMed:11738032). Its activation dampens the excitatory events that elevate the cytosolic Ca(2+) concentration and/or depolarize the cell membrane (PubMed:11738032). It therefore contributes to repolarization of the membrane potential (PubMed:11738032). Essential for the regulation of neurotransmitter release at synapses (PubMed:11738032, PubMed:28168949). Homotetramer; which constitutes the calcium-activated potassium channel. Expressed in synaptic regions of the nervous system including in both the nerve ring and nerve cords, as well as in the body-wall and vulval muscle. The S4 segment, which is characterized by a series of positively charged amino acids at every third position, is part of the voltage-sensor. The pore-forming domain (also referred as P region) is imbedded into the membrane, and forms the selectivity filter of the pore. It contains the signature sequence of potassium channels that displays selectivity to potassium (By similarity). The RCK N-terminal domain mediates the homotetramerization, thereby promoting the assembly of monomers into functional potassium channel. It includes binding sites for Ca(2+) and Mg(2+) (By similarity). The calcium bowl constitutes one of the Ca(2+) sensors and probably acts as a Ca(2+)-binding site. Phosphorylated. Its activity is activated by ethanol, leading to the inhibition of neuronal activity. Belongs to the potassium channel family. Calcium-activated (TC 1.A.1.3) subfamily. Slo sub-subfamily.