Carboxypeptidases are proteolytic enzymes that are known to modify and degrade bioactive and dietary peptides. While many members of this family of enzymes have been characterized for decades, some members are poorly understood. Carboxypeptidase O (CPO) is one such poorly characterized enzyme. Recent experiments have shown that CPO is highly expressed by intestinal epithelial cells, where it is anchored to cellular membranes by a glycosylphosphatidylinositol group. It is found on the external plasma membrane, suggesting a role in digestion. The identity of associated internal membranes is not clear. Current research is investigating the subcellular localization of CPO and the manner in which this enzyme is regulated.
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