Carbonic anhydrases (CAs) are members of a large family of zinc metalloenzymes responsible for catalyzing the reversible hydration of carbon dioxide. CAs show extensive diversity in their distribution and subcellular localization. They are involved in a variety of biological processes, including calcification, bone resorption, respiration, acid-base balance and the formation of aqueous humor, saliva, gastric juice and cerebrospinal fluid. CA XI, also referred to as carbonic anhydrase-related protein 11 precursor (CA-RP XI) or carbonic anhydrase-related protein 2 (CA-RP II), is a member of the carbonic anhydrase family that lacks two of the three Zn-binding motifs essential for carbonic anhydrase activity. For this reason, CA XI does not exhibit catalytic activity. It is expressed primarily in brain but is also found in spinal cord and thyroid. CA XI may play a role in brain development.

Tissue specificity:Expressed abundantly in the brain with moderate expression also present in spinal cord and thyroid.