Mitochondrial membrane carrier protein that mediates the import of NAD(+) into mitochondria (PubMed:32906142, PubMed:33087354, PubMed:33262325). Mitochondrial NAD(+) is required for glycolysis and mitochondrial respiration (PubMed:32906142, PubMed:33087354, PubMed:33262325). Compared to SLC25A52, SLC25A51-mediated transport is essential for the import of NAD(+) in mitochondria (PubMed:32906142). The transport mechanism, uniport or antiport, its electrogenicity and substrate selectivity, remain to be elucidated. . This is the function of Ensembl gene identifier ENSG00000122696 (SLC25A51, solute carrier family 25 member 51).