Mediates electroneutral potassium-chloride cotransport in mature neurons and is required for neuronal Cl(-) homeostasis. As major extruder of intracellular chloride, it establishes the low neuronal Cl(-) levels required for chloride influx after binding of GABA-A and glycine to their receptors, with subsequent hyperpolarization and neuronal inhibition (By similarity). Involved in the regulation of dendritic spine formation and maturation (PubMed:24668262). Inhibited by WNK3. Homomultimer and heteromultimer with other K-Cl cotransporters. Interacts with AP2A1 (By similarity). Brain specific. Detected in neuronal cells. The disease is caused by variants affecting the gene represented in this entry. Disease susceptibility is associated with variants affecting the gene represented in this entry. Inhibited by furosemide and bumetanide. Belongs to the SLC12A transporter family.