Mitochondrial carbonic anhydrase that catalyzes the reversible conversion of carbon dioxide to bicarbonate/HCO3 (PubMed:24530203, PubMed:8356065). Mitochondria are impermeable to HCO3, and thus this intramitochondrial carbonic anhydrase is pivotal in providing HCO3 for multiple mitochondrial enzymes that catalyze the formation of essential metabolites of intermediary metabolism in the urea and Krebs cycles (PubMed:24530203). {ECO:0000269|PubMed:24530203, ECO:0000269|PubMed:8356065}. This is the function of ENSG00000174990 (CA5A, carbonic anhydrase 5A).