Carbonic anhydrase XIII

Carbonic anhydrase XIII (CA XIII) is a recently identified member of the α-carbonic anhydrase family and a cytosolic enzyme with conserved structural and catalytic features. Since its discovery in 2004, its gene organization, protein structure, catalytic mechanism, and inhibition profile have been extensively characterized. CA XIII exhibits moderate catalytic activity compared to other cytosolic isozymes, with differences in proton transfer dynamics accounting for its distinct efficiency. The enzyme is widely expressed in human tissues, particularly in epithelial and reproductive systems, suggesting roles in pH regulation, bicarbonate metabolism, and tissue homeostasis. Despite this, its physiological function remains incompletely defined. Emerging evidence links CA XIII to pathological processes, including its downregulation in colorectal cancer and tumor-suppressive effects in breast cancer models. In contrast, studies in acute myeloid leukemia indicate a context-dependent role in cell proliferation and drug response. Associations with inflammatory conditions, aging, and cognition further suggest broader biological relevance. Pharmacologically, CA XIII is sensitive to sulfonamide inhibitors and activators, making it a relevant target for isozyme-selective drug design. However, the lack of in vivo models remains a major limitation, highlighting the need for integrative future studies.