Mitochondrial iron transporter that mediates iron uptake. Probably required for heme synthesis of hemoproteins and Fe-S cluster assembly in non-erythroid cells. The iron delivered into the mitochondria, presumably as Fe(2+), is then probably delivered to ferrochelatase to catalyze Fe(2+) incorporation into protoprophyrin IX to make heme (Probable). Isoform 1 and isoform 2 are both localized in the mitochondrion. Ubiquitously expressed at low level. Expressed at higher level in heart, liver, kidney and testis. Expression does not vary during erythroid maturation. Belongs to the mitochondrial carrier (TC 2.A.29) family.