Plasma membrane calcium-transporting ATPase 3 (ATP2B3, also known as PMCA3) belongs to the IIB subfamily of P-type ATPases, whose members are plasma membrane Ca2+ ATPases (PMCAs) that catalyse the hydrolysis of ATP coupled with the transport of calcium. PMCA3 is expressed in brain, particularly abundant in the choroid plexus. It has high calmodulin affinity compared to other PMCAs. Mutations in the PMCA3 genes have been linked to the X-linked congenital cerebellar ataxia.