Magnesium transporter that mediates the influx of magnesium into the mitochondrial matrix (PubMed:11401429, PubMed:18384665). Required for normal expression of the mitochondrial respiratory complex I subunits (PubMed:18384665). Has the ability to complement a deletion of MRS2 in S.cerevisiae and partly restore mitochondrial magnesium concentrations. Belongs to the CorA metal ion transporter (MIT) (TC 1.A.35) family.