Carbonic anhydrase 4 (None)

Carbonic anhydrase 4 (CA4) is a zinc metalloenzyme that catalyzes the reversible hydration of carbon dioxide (CO2 + H2O <-> HCO3- + H+). It is a GPI-anchored membrane protein expressed on the luminal surfaces of pulmonary capillaries, proximal renal tubules, and capillary endothelial cells. CA4 plays a key role in pH regulation and CO2 transport across membranes, contributing to respiration, acid-base balance, and synaptic function. Mutations or dysfunctions have been implicated in inherited renal abnormalities. Several drugs inhibit CA isoforms including CA IV, such as acetazolamide and topiramate.

Inhibition of carbonic anhydrase activity, thereby reducing the conversion of CO2 to bicarbonate and protons. Acetazolamide and Topiramate are direct inhibitors. Bumetanide/Furosemide can indirectly affect related pathways, but are not direct inhibitors.