Carbonic Anhydrase IX/CA9: Proteins and Enzymes

Carbonic anhydrases catalyze the reversible reaction of CO2 + H2O = HCO3- + H+, which is fundamental to many processes such as respiration, renal tubular acidification and bone resorption. Human members of the CAs are secreted (CA6), membrane-bound (CA4, 9 to 12 and 14), cytosolic (CA1 to 3, 7, 8 and 13) or mitochondrial (CA5A and 5B). Some CAs may serve as markers for tumors and hypoxia. A subset of CAs lack CA activity due to point mutations but retain esterase function.