GENOMIC ORGANIZATION OF THE FMRFAMIDE GENE IN LYMNAEA - MULTIPLE EXONS ENCODING NOVEL NEUROPEPTIDES

Based on the sequencing of genomic and cDNA clones, we were able to de termine that the FMRFamide gene consists of five exons covering at lea st 20 kb and predict the presence of further novel peptides. The exons are alternatively spliced: exon I (hydrophobic leader sequence) to ex on II (tetrapeptides) and exon I to exons III (heptapeptides), IV, and V. A cDNA clone encoding the heptapeptides is described and has also been shown to encode further novel peptides SKPYMRFamide, HDYMRFamide, and SSFPRYamide. Analysis of the right internal parietal nerve using mass spectrometry showed that the novel peptide SKPYMRFamide was cleav ed from the precursor. This peptide excites neurons, suggesting a phys iological function in the CNS.