Acts as a Mg(2+) transporter. Can also transport other divalent cations such as Fe(2+), Sr(2+), Ba(2+), Mn(2+) and Co(2+) but to a much less extent than Mg(2+) (By similarity). Homodimer. Recruited to the cell membrane in response to low extracellular magnesium. Belongs to the NIPA (TC 2.A.7) family. Lacks one of the 9 transmembrane regions, which are conserved features of the family.