Potassium intermediate-conductance calcium-activated channel protein 4 (KCNN4) (IK1)

Potassium intermediate-conductance calcium-activated channel protein 4 (KCNN4), frequently referred to as IK1 or KCa3.1, is a transmembrane protein that forms a voltage-independent potassium channel activated by intracellular calcium levels (UniProt Q92482). It is widely expressed in non-excitable cells such as red blood cells, T-lymphocytes, B-lymphocytes, and various epithelial and endothelial cells (NCBI Gene 3783). In erythrocytes, KCNN4 is known as the Gardos channel, where its activation leads to potassium and water loss, causing cell dehydration—a hallmark of sickle cell disease (PubMed: 18063757). In the immune system, the channel helps maintain the electrochemical gradient necessary for sustained calcium signaling during T-cell activation and proliferation (PubMed: 17110104). Consequently, KCNN4 has emerged as a therapeutic target for sickle cell anemia, autoimmune diseases, and fibroproliferative disorders. While the KCNN4 inhibitor senicapoc showed promise in reducing hemolysis in sickle cell patients, it failed to meet primary clinical endpoints for pain crisis reduction, leading to a shift in focus toward its potential in treating asthma and organ fibrosis (PubMed: 21415308).

Other names

KCa3.1IKCa1SK4Gardos channelKCNN4hIK1Intermediate-conductance calcium-activated potassium channel protein 4

Inhibition of the intermediate-conductance calcium-activated potassium channel to prevent potassium efflux, thereby modulating cell volume in erythrocytes and membrane potential in leukocytes and fibroblasts.