Potassium channel activated by both membrane depolarization or increase in cytosolic Ca(2+) that mediates export of K(+). Its activation dampens the excitatory events that elevate the cytosolic Ca(2+) concentration and/or depolarize the cell membrane. It therefore contributes to repolarization of the membrane potential. Kinetics are determined by alternative splicing, phosphorylation status and its combination interaction with Slob and 14-3-3-zeta. While the interaction with Slob1 alone increases its activity, its interaction with both Slob1 and 14-3-3-zeta decreases its activity. Homotetramer; which constitutes the calcium-activated potassium channel (By similarity). Interacts with Slip1. Interacts with Slob, and, indirectly with 14-3-3-zeta via its interaction with Slob. Interacts with Pka-C1 and Src kinases, which can bind simultaneously to it. Additional isoforms seem to exist. Expressed in muscle cells, neurons of the CNS and PNS, mushroom bodies, a limited number of cells in embryonic and larval midgut and in epithelial-derived tracheal cells. During pupariation and embryogenesis, it is expressed in muscles many hours prior to the appearance of functional channels. 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. Phosphorylation may be mediated by both PKA and SRC kinases, which activate the channel activity. Phosphorylation by PKA is however unclear. Indeed, although modulation of channel activity requires Pka-C1, it does not interacts with the whole PKA holoenzyme. Moreover, modulation of activity does not depend upon phosphorylation of Ser-978. Belongs to the potassium channel family. Calcium-activated (TC 1.A.1.3) subfamily. Slo sub-subfamily. Extended N-terminus.