High-conductance magnesium-selective channel that mediates the influx of magnesium into the mitochondrial matrix (PubMed:12628916, PubMed:17827224, PubMed:20653776, PubMed:23999289). Essential for the splicing of mRNA group II introns in mitochondria by affecting mitochondrial magnesium concentrations, which are critical for group II intron splicing. It also suppresses a variety of mitochondrial intron mutations and its absence may disturb the assembly of mitochondrial membrane complexes (PubMed:11544180). Homopentamer (PubMed:23999289). Forms homooligomers. Interacts with MFM1 (PubMed:20653776). Present with 768 molecules/cell in log phase SD medium. Belongs to the CorA metal ion transporter (MIT) (TC 1.A.35) family. Was originally (PubMed:1551905 and PubMed:8252639) identified in genetic screens for bona fide RNA splicing factors, but it has later been shown that not the MRS2 protein per se but certain magnesium concentrations are essential for group II intron splicing.