Acts as a Mg(2+) transporter. Can also transport other divalent cations such as Ba(2+), Mn(2+), Sr(2+) and Co(2+) but to a much less extent than Mg(2+). May be a receptor for ligands (trioxilins A3 and B3) from the hepoxilin pathway (By similarity). Up-regulated by low magnesium ion levels. Belongs to the NIPA family.