CNPs are ancient members of the natriuretic peptide family, which is characterized by the absence of C-terminal tail
extensions from the intramolecular ring. In mammals, CNP
is highly expressed in the brain, vascular endothelial cells, and
chondrocytes, and acts locally as a paracrine/autocrine
factor. CNP was isolated in 1990 from the killifish brain, and
shortly thereafter from the pig brain. Four distinct CNPs
(CNP1–4) were then discovered in 2003 from teleost
genome databases. Later, comparative genomic analyses
inferred that only CNP4 is retained in mammals, CNP1
and CNP3 in birds, CNP3 and CNP4 in amphibians,
CNP1–4 in most teleosts, CNP3 in elasmobranchs, and
CNP4 or CNP4-like NP in cyclostomes.
