Pendrin

Pendrin is an anion exchange protein that in humans is encoded by the SLC26A4 gene (solute carrier family 26, member 4). Pendrin was initially identified as a sodium-independent chloride-iodide exchanger with subsequent studies showing that it also accepts formate and bicarbonate as substrates. Pendrin is similar to the Band 3 transport protein found in red blood cells. Pendrin is the protein which is mutated in Pendred syndrome, which is an autosomal recessive disorder characterized by sensorineural hearing loss, goiter and a partial organification problem detectable by a positive perchlorate test.

Pendrin orthologs are responsible for mediating the electroneutral exchange of chloride (Cl⁻) for bicarbonate (HCO₃⁻) across a plasma membrane in the chloride cells of freshwater fish, and show changes in expression in response to salinity change in the gills of Atlantic stingrays.

By phylogenetic analysis, pendrin has been found to be a close relative of prestin present on the hair cells or organ of corti in the inner ear. Prestin is primarily an electromechanical transducer but pendrin is an ion transporter.