Purification and characterization of a novel excitatory peptide from Conus distans venom that defines a novel gene superfamily of conotoxins

摘要

An excitatory peptide, di16a, with 49 amino acids and ten cysteine residues was purified and characterized from the venom of Conus distans. Five AA residues were modified: one γ–carboxyglutamate (Gla), and four hydroxyproline (Hyp) residues. A cDNA clone encoding the precursor for the peptide was characterized; the peptide has a novel cysteine framework and a distinctive signal sequence that differs from any other conotoxin superfamily. The peptide was chemically synthesized and folded, and synthetic and native materials were shown to co-elute. Injection of the synthetic peptide causes a hyperexcitable phenotype in mice greater than three weeks of age at lower doses, and lethargy at higher doses. The peptide defines both a previously-uncharacterized gene superfamily of conopeptides, and a new Cys pattern with three vicinal Cys residues.