Structure of the cDNA encoding the precursor for the neuropeptide FMRFamide in the bivalve mollusc Mytilus edulis.

FMRFamide immunoreactivity is widespread in the tissues of bivalve molluscs, but some of this immunoreactivity may represent distinct related peptides (FaRPs) rather than the exact tetrapeptide FMRFamide. We have cloned the first full-length cDNA encoding the precursor protein for FMRFamide from this class of molluscs to investigate the possibility that additional peptides may be produced. The precursor contains one copy each of NFLRFamide, FLRFamide, ALAGDHFFRFamide and 16 copies of FMRFamide. This precursor is expressed in all three ganglia of the central nervous system. Since the gene encoding the FMRFamide precursor in pulmonate molluscs is alternatively spliced to give two distinct messages, we searched for evidence that the FMRFamide gene of Mytilus is also alternatively spliced. No evidence of alternative splicing was found.