Conantokins are small, γ-carboxylate-rich peptides derived from the venoms of the Conus predatory marine snails. Several members of this peptide family have been reported, including conantokin (con)-G, con-T, con-R, con-L and so on. In mammals, they act as the potent and selective antagonists of NMDAR. Despite the high sequence homology that exists among conantokins, distinct differences have been reported in their subunit selective properties.  >> Read More

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Conatokins-T, a 21-animo acid peptide which induces sleep-like symptoms in young mice was purified from the venom of the fish-hunting cone snail, Conus tulipa. The amino acid sequence of the peptide was determined and verified by chemical synthesis. The peptide has 4 residues of the modified amino acid, ycarboxyglutamate (Gla). The sequence of the peptide is: Gly-Glu-Gla-GIa-Tyr-Gln-Lys-Met-Leu-Gla-AsnLeu-Arg-Gla-Ala-Glu-Val-Lys-Lys-Asn-Ala-NHz. Conantokin-T inhibits N-methyl-D-aspartate (NMDA) receptor-mediated calcium influx in central nervous system neurons. This observation suggests that like conantokin-G (a homologous Conus peptide with recently identified NMDA antagonist activity) conantokin-T has NMDA antagonist activity. A sequence comparison of conantokins-T and -G identifies the 4 GIa residues and the N-terminal dipeptide sequence as potential key elements for the biological activity of this peptide.

Conantokin-T. A gamma-carboxyglutamate containing peptide with N-methyl-d-aspartate antagonist activity

Conantokin-T (Con-T), which contains four Gla residues, is a 21-residue peptide isolated from C. tulipa venoms, sharing about 40% sequence homology with Con-G. Both Con-G and Con-T in-duce a sleeping effect in young mice but hyperactive behaviour in old mice when administered by intracranial injection.

Role of modified glutamic acid in the helical structure of conantokin-T