Isolation of Lys-conopressin-G from the venom of the worm-hunting snail, Conus imperialis

Vasopressin homologs have previously been isolated from the venom of fish-hunting cone snails. We investigated whether a vasopressin-like peptide is found in the worm-hunter, Conus imperialis. Using i.c. injections in mice, we isolated a peptide from the venom of C. imperialis which induces scratching and grooming behavior characteristic of the conopressins. Biochemical characterization showed that this peptide is identical to Lys-conopressin-G. The results led us to speculate that the vasopressin-like peptides in Conus venoms may be examples of an evolving conversion of endogenous peptides for specialized venom uses.