Inducers, bioactive peptides, examples

Finally, an outstanding example of research into marine bioactive peptides is that of the conotoxin peptides derived from the venom of marine snails of the genus Conus [159]. The initial propeptide is processed by both post-translational modification and proteolytic cleavage into a variety of small peptides which are 10-50 amino acids in length [160, 161]. Research into potential therapeutic applications of the conotoxins has shown that a number of these peptides interact uniquely with ion channels to induce a wide variety of pharmacological effects in mammalian systems [162-164]. General reviews of the conotoxins are available [160, 165], as well as more-detailed reviews of their structures [166] and potential therapeutic uses [166-168]. 

The presence of proctolin in the reproductive tract of a variety of insects and the action of this peptide on such tissues has been a current focus for many studies. The visceral muscles of the oviducts of Locusta migratoria. for example, are remarkably sensitive to proctolin (30)- Amounts of the peptide as low as 2 fmol induce a tonic contraction that is dose-dependent up to 200 fmol. A proctolin-like immunoreactive substance was found in the axons of nerves leading to the oviduct as well as in a number of cell bodies in the Vllth abdominal ganglion. Moreover, reverse-phase HPLC of tissue extracts of oviducts, oviducal nerves, and the Vllth abdominal ganglia indicate that the proctolin-like bioactive substance co-elutes with authentic proctolin. The peptide was present in areas of the oviduct that receive extensive innervation while it was ten-fold less in areas that receive little or no innervation. 

---