THE BUCCALIN-RELATED NEUROPEPTIDES - ISOLATION AND CHARACTERIZATION OF AN APLYSIA CDNA CLONE ENCODING A FAMILY OF PEPTIDE COTRANSMITTERS

The buccalin-related peptides, buccalin A and buccalin B, are members of a family of cotransmitters that modulate neuromuscular transmission in Aplysia. In this study, a third buccalin-related peptide, buccalin C, was purified from neuronal elements in the accessory radula closer , a muscle involved in the animal's feeding behavior. Oligonucleotide probes based upon the amino acid sequence of buccalin C were used to i solate cDNA clones that encode a buccalin precursor polypeptide. The b uccalin precursor contains 19 distinct buccalin-related peptides, seve ral of which are present in multiple copies. The buccalin gene appears to be present in a single copy, with one allele containing a small in sert. Expression of this gene occurs in a tissue-specific manner and m RNA transcripts are abundant within neurons in the Aplysia CNS. This l arge family of neuropeptides may exert extraordinarily complex modulat ory actions at synapses where they serve as cotransmitters.