Enables sodium:iodide symporter activity. Involved in iodide transmembrane transport and sodium ion transport. Is active in plasma membrane. Human ortholog(s) of this gene implicated in congenital hypothyroidism and thyroid dyshormonogenesis 1. Orthologous to human SLC5A5 (solute carrier family 5 member 5). [provided by Alliance of Genome Resources, Apr 2022]