Carbonic Anhydrase VI (CA6)

Carbonic anhydrase 6 is one of several isozymes of carbonic anhydrase. This protein is found only in salivary glands and saliva and protein may play a role in the reversible hydratation of carbon dioxide though its function in saliva is unknown.The clones identified a 1.45-kb mRNA that was present in high levels in parotid submandibular salivary glands but absent in other tissues such as sublingual gland, kidney, liver, and prostate. The mature CA VI protein has 291 amino acids, compared to the 259 or 260 residues of the cytoplasmic isozymes; most of the extra amino acids present are in the carboxyl terminal region. The CA VI protein has 35% sequence identity with human CA II, while residues involved in the active site of the enzymes have been conserved. Southern analysis of human DNA indicated that there is only 1 gene coding for CA VI.