ASNA1, also as known as ARSA and TRC40, is the human homolog of the bacterial arsA, a member of the ATPase superfamily. ArsA and ArsB have been postulated to form a membrane complex which functions as an anion-translocating. It recognizes and selectively binds the transmembrane domain of TA proteins in the cytosol. This complex then targets to the endoplasmic reticulum by membrane-bound receptors, where the tail-anchored protein is released for insertion. This process is regulated by ATP binding and hydrolysis. ArsA hydrolyses ATP in the presence of its anionic substrate antimonite and produces resistance to arsenite and antimonite. The active form of ArsA is a homodimer with four nucleotide binding sites, two from each monomer.