CA2 is one of several (at least 7) isozymes of carbonic anhydrase. Carbonic anhydrase catalyzes reversible hydration of carbon dioxide. Defects in this enzyme are associated with osteopetrosis and renal tubular acidosis. All CA can be divided into 3 distinct classes (α, β, and γ) that evolved independently and have no significant homology in sequence and overall folding. All functional CA catalyze the reversible hydration of CO2 into HCO3- and H+ and contain a zinc atom in the active sites essential for catalysis. CA2 is a cytosolic member of the α class. It is the most widely distributed isoform among the mammalian CAs. Defects in CA2 are associated with osteopetrosis and renal tubular acidosis. Elevated expression of CA2 is observed in patients with Alzheimer’s disease and the developing brains of Down syndrome patients.
