Localization of Carboxypeptidase O in Madin-Darby Canine Kidney Cells

Carboxypeptidases are enzymes that trim the carboxy-terminal ends of proteins. Carboxypeptidase O (CPO) is a recently discovered enzyme that was proposed to be associated with lipid droplets. Lipid droplets are organelles found in the cytosol of the cell that carry out different roles like storing metabolic energy and protein degradation. To test if CPO and lipid droplets were associated, we used immunocytochemistry and lipid droplet staining of Madin-Darby canince kidney (MDCK) cells. Our data shows that lipid droplets can be detected with both BODIPY 493/503 and Nile Blue dye. CPO is associated with lipid droplets, but CPO does not affect the number of lipid droplets. Studies show that lipid droplet proteins contain potential cleavage sites for CPO. This information can possibly help in the advancement of research of metabolic disease.