First, proprotein convertases cut the precursor at specific sites to generate intermediates containing C-terminal basic residues (lysine and/or arginine).

[7] Carboxypeptidase E is found in brain and throughout the neuroendocrine system, including the endocrine pancreas, pituitary, and adrenal gland chromaffin cells.

Carboxypeptidase E is found in all species of vertebrates that have been examined, and is also present in many other organisms that have been studied (nematode, sea slug).

It is thought that a related enzyme (carboxypeptidase D) also contributes to neuropeptide processing and gives rise to the mature peptides in the Cpefat mice.

One patient with extreme obesity (Body Mass Index >50) was found to have a mutation that deleted nearly the entire CPE gene.

[11] This patient had intellectual disability (inability to read or write) and had abnormal glucose homeostasis, similar to mice lacking CPE activity.