Different molecular forms of C-type natriuretic peptide isolated from the brain and heart of an elasmobranch, Triakis scyllia.
The presence of a C-type natriuretic peptide (CNP) has been reported in the brain of mammals, birds, amphibians and teleost fishes, mostly as a 22-residue peptide (CNP-22). In the present study, we attempted to isolate natriuretic peptides from an elasmobranch, Triakis scyllia, using a chick rectum-relaxant assay, and different molecular forms of CNP were found in the brain and heart. Only CNP-22 was recovered from the brain, as is the case in other vertebrates. A large amount of prohormone (proCNP or CNP-115) and small amounts of its C-terminal peptides (CNP-38 and CNP-39) were isolated from the atrium and ventricle, however. No CNP-22 was recovered from the heart. Natriuretic peptides other than CNP were not isolated from Triakis heart and brain by the rectum-relaxant assay. The 22 residues at the C-terminal region of proCNP, i.e. CNP-22, were well conserved when Triakis and mammals were compared, although the sequence homology of the N-terminal segment of proCNP was very low. Not only was CNP-22 identical but the N-terminal segments of proCNP were also quite similar when Triakis and another elasmobranch, Scyliorhinus canicula, were compared. These data suggest that, in elasmobranchs, CNP is a primary hormone in the natriuretic peptide family, and also that CNP is processed differently in the brain and heart.
Suzuki
R
R
Department of Physiology, Kitasato University School of Medicine, Kanagawa, Japan.
Takahashi
A
A
Takei
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D005399:Fishes / Q000378:metabolism*; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000235:genetics; D016415:Sequence Alignment
D009419:Nerve Tissue Proteins; D020098:Natriuretic Peptide, C-Type