Carboxypeptidase N subunit 1 (CPN1)

Carboxypeptidase N subunit 1 (CPN1) encodes the active catalytic chain of plasma carboxypeptidase N, a tetrameric zinc metalloprotease involved in cleaving C-terminal lysine and arginine residues from circulating peptides. This activity is essential for inactivation of inflammatory mediators such as anaphylatoxins and kinins, thus modulating immune and inflammatory responses and maintaining vascular homeostasis. Mutations or deficiencies in CPN1 can lead to painful, life-threatening conditions such as angioedema due to impaired clearance of vasoactive peptides. The full enzyme is a tetramer composed of two CPN1 catalytic subunits and two larger, non-catalytic regulatory subunits, the latter containing leucine-rich repeats important for protein–protein interactions. CPN1’s physiological substrates include bradykinin, anaphylatoxins, and SDF-1α, underlining its central function in peptide-mediated signaling.

Other names

Carboxypeptidase N catalytic chainCPN1Carboxypeptidase N, polypeptide 1Plasma carboxypeptidase BSerum carboxypeptidase NAnaphylatoxin inactivatorKininase-1Arginine carboxypeptidaseLysine carboxypeptidaseSCPNCarboxypeptidase K

Drugs or inhibitors targeting CPN1 would act via inhibition of carboxypeptidase activity, decreasing inactivation of kinins/anaphylatoxins, or modulating inflammatory peptide clearance.