SK3 (small conductance calcium-activated potassium channel 3) also known as KCa2.3 is a protein that in humans is encoded by the KCNN3 gene.
SK3 is a small-conductance calcium-activated potassium channel partly responsible for the calcium-dependent after hyperpolarisation current (IAHP). It belongs to a family of channels known as small-conductance potassium channels, which consists of three members – SK1, SK2 and SK3 (encoded by the KCNN1, 2 and 3 genes respectively), which share a 60-70% sequence identity. These channels have acquired a number of alternative names, however a NC-IUPHAR has recently achieved consensus on the best names, KCa2.1 (SK1), KCa2.2 (SK2) and KCa2.3 (SK3). Small conductance channels are responsible for the medium and possibly the slow components of the IAHP.