1.C.46 The C-type Natriuretic Peptide (CNP) Family

C-type natriuretic peptides (CNPs) are widely distributed in the mammalian central nervous system, the brain, endothelial cells, kidney, and the GI tract. They are also synthesized by many other animals such as fish, frogs, snakes and the platypus. These secreted peptides may play a role in cytokine-associated disorders, septic shock and renal failure in mammals. The CNP from platypus (Ornithorhynchus anatinus) venom yields sustained tonic relaxation of rat uterus. Both human CNP-22 (HsCNP-22) and the highly similar platypus venom CNP-39 (OaCNP-39) form weakly cation-selective, voltage gated, large conductance channels in artificial bilayers. The HsCNP and OaCNP-39 channels exhibit inward rectification, with permeabilities to K+> Na+> Cs>> choline.

The CNP precursor proteins are large, i.e. >100 residue proteins which can be degraded to small peptides, the active channel-forming constituents being derived from the C-termini. For example, the human CNP (126aas) degrades to three peptides CNP-22, CNP-29 and CNP-53, all derived from the C-terminus of the precursor protein.

The transport reaction catalyzed by the oligomeric channels derived from CNP peptides is:

cations (in) cations (out)



Kourie, J.I. (1999). A component of platypus (Ornithorhynchus anatinus) venom forms slow-kinetic cation channels. J. Mem. Biol. 172: 37-45.

Kourie, J.I. (1999). Calcium dependence of C-type natriuretic peptide-formed fast K+ channel. Am. J. Physiol. 277: C43-C50.

Kourie, J.I. (1999). Characterization of a C-type natriuretic peptide (CNP-39)-formed cation-selective channel from platypus (Ornithorhynchus anatinus) venom. J. Physiol. 518: 359-369.

Kourie, J.I. (1999). Synthetic mammalian C-type natriuretic peptide forms large cation channels. FEBS Lett. 445: 57-62.


TC#NameOrganismal TypeExample
1.C.46.1.1CNP precursor protein (CNP-22 and CNP-29) Animals CNP precursor protein of Homo sapiens
1.C.46.1.2Full snake Bradykinin-potentiating and C-type natriuretic peptides (265aas)


Bradykinin-potentiating peptide of Bothrops jararaca (Q9PW56)


TC#NameOrganismal TypeExample
1.C.46.2.1Cardiac Peptide (145aas)


Cardiac peptide of Salmo salar (Q78AW6)

1.C.46.2.2Full ventricular natriuretic peptide precursor


Full ventricular natriuretic peptide of Acipenser transmontanus (P83962)