Abstract Sulfate (SO42−) is a pivotal inorganic anion with essential roles in mammalian physiology. NaS1, a member of solute carrier 13 family and divalent anion/sodium symporter family, functions as a Na+-sulfate cotransporter, facilitating sulfate (re)absorption across renal proximal tubule and small intestine epithelia. While previous studies have linked several human disorders to mutations in the NaS1 gene, its transport mechanism remains unclear.