Abstract
Many biologically active peptides (neurohormonal or regulatory peptides) have been shown to be amidated at the C terminus. Several techniques were observed for the detection of amidated C- terminal amino acids, which aided in the isolation of a series of novel regulatory peptides. Porcine brain and gut contained large amounts of a peptide resembling pancreatic polypeptide (PP). Brain PP-like peptide differed from a peptide isolated from the gut (PYY), and was referred as “neuropeptide Y” (NPY). NPY is located in neuronal elements not only in the brain but also in the periphery and in cells of the adrenal medulla. The amino acid sequence of the human NPY precursor is predicted on the basis of the nucleotide sequence of DNA complementary to NPY mRNA isolated from a pheochromocytoma. In the precursor, the NPY sequence is at the N-terminal end, immediately downstream from the signal peptide, with a C-terminal extension of 30 amino acid residues linked to NPY by a pair of basic amino acids. In the sympathetic nerve fibers, there is evidence of partial costorage of (noradrenaline) NA and NPY in large, dense-cored vesicles—the small, electron-lucent vesicles seem to harbor only NA. In perivascular nerves, NPY seems to play a functional role as a vasoconstrictor per se and as a cotransmitter potentiating the contractile response of the vascular smooth muscle to NA.
