SLC4A3, also known as anion exchange protein 3 (AE3), is a member of the bicarbonate transporter family. It predominantly transports chloride and bicarbonate. The SLC4A3 protein is widely distributed in the brain, heart, retina, smooth muscle, kidney, and gastrointestinal tracts. Deletion of the slc4a3 gene in mice results in inner retinal defects. In humans, the functional defects of the SLC4A3 protein caused by the A867D mutation are suggested to promote neuronal hyperexcitability in the brain and generate seizures.