Purification, characterization, synthesis, and cloning of the lockjaw peptide from Conus purpurascens venom.

The major groups of Conus peptides previously characterized from fish-hunting cone snail venoms (the alpha-, mu-, and omega-conotoxins) all blocked neuromuscular transmission. A novel activity, the "lockjaw peptide", from the fish-hunting Conus purpurascens, caused a rigid (instead of flaccid) paralysis in fish and increased excitability at the neuromuscular junction (instead of a block). We report the purification, biological activity, biochemical and preliminary physiological characterization, and chemical synthesis of the lockjaw peptide and the sequence of a cDNA clone encoding its precursor. Taken together, the data lead us to conclude that the lockjaw peptide is a vertebrate-specific delta-conotoxin, which targets voltage-sensitive sodium channels. The sequence of the peptide, which we designate delta-conotoxin PVIA, is (O = 4-trans-hydroxyproline) EACYAOGTFCGIKOGLCCSEFCLPGVCFG-NH2. This is the first of a diverse spectrum of Conus peptides which are excitotoxins in vertebrate systems.