Catalyzes the electroneutral exchange or flux of physiologically important metabolites such as dicarboxylates (malonate, malate, succinate), inorganic sulfur-containing anions, and phosphate, across mitochondrial inner membrane (PubMed:3355813, PubMed:9733776, PubMed:29211846). Plays an important role in gluconeogenesis, fatty acid metabolism, urea synthesis, and sulfur metabolism, particularly in liver, by supplying the substrates for the different metabolic processes (PubMed:9733776). Regulates fatty acid release from adipocytes, and contributes to systemic insulin sensitivity (By similarity). (S)-malate(in) + phosphate(out) = (S)-malate(out) + phosphate(in) (S)-malate(in) + malonate(out) = (S)-malate(out) + malonate(in) (S)-malate(in) + succinate(out) = (S)-malate(out) + succinate(in) (S)-malate(in) + sulfate(out) = (S)-malate(out) + sulfate(in) malonate(out) + phosphate(in) = malonate(in) + phosphate(out) phosphate(in) + succinate(out) = phosphate(out) + succinate(in) phosphate(in) + sulfate(out) = phosphate(out) + sulfate(in) malonate(out) + succinate(in) = malonate(in) + succinate(out) Expressed most strongly in liver, then kidney, and at lower levels in heart and brain. Belongs to the mitochondrial carrier (TC 2.A.29) family.