Carboxypeptidase E is found in brain and throughout the neuroendocrine system, including the endocrine pancreas, pituitary, and adrenal gland chromaffin cells. Within cells, carboxypeptidase E is present in the secretory granules along with its peptide substrates and products. Carboxypeptidase E is a  glycoprotein that exists in both membrane-associated and soluble forms. The membrane-binding is due to an amphiphilic α-helix within the C-terminal region of the protein.