The Aplysia FMRFamide gene encodes sequences related to mammalian brain peptides.

We have characterized a precursor protein which gives rise to the neuropeptide Phe-Met-Arg-Phe-amide (FMRFamide) by determining the nucleotide sequence of a genomic and five cDNA clones. The 597-amino-acid protein contains 28 copies of the tetrapeptide FMRFamide, a single Phe-Leu-Arg-Phe-amide (FLRFamide), and other sequences flanked by paired basic residues, some of which have homologies to mammalian brain peptides. The data presented suggest the genes encoding pro-opiomelanocortin, pre-pro-enkephalin, and the hypothalamic releasing factor, cortico-releasing factor (CRF), arose from a common ancestral gene.