Conus imperialis

Nielsen, D.B., Dykert, J., Rivier, J.E., and McIntosh, J.M. (1994) Isolation of Lys-conopressin-G from the venom of the worm-himting snail Conus imperialis. Toxicon, 32, 845-848. 

Craig, A.G., Jimenez, E.C., Dykert, J., Nielsen, D.B., Gulyas, J., Abogadie, F.C., Porter, J., Rivier, J.E., Cruz, L.J., Oliveras, B.M., and McIntosh, J.M. (1997) A novel post-translational modification involving bromination of tryptophan identification of the residue, L-6-bromotryptophane, in peptides from Conus imperialis and Conus radiatus venom. J. Biol. Chem., 272, 4689-4698. 

With the exception of a-conotoxin SII from Conus striatus, all a-conotoxins have the cysteine pattern, CC—C—C (Myers et al., 1993) (see Table 4). Peptides from the fish-hunting species, C geographus, C. striatus and C. magus, have the consensus core sequence CC(N/H)PACGXX(Y/F)XC and two disulfide bonds that connect Cys to Cys and Cys to Cys. Comparison with the a-conotoxins recently isolated from C. pennaceus, a mollusc-hunter, and C. imperialism a worm-hunter, indicates variations in the size of the intercysteine loops. The second loop has seven amino acid residues in a-conotoxins PnIA and PnIB from C pennaceus (Fainzilber et al., 1994), and only three residues in a-conotoxin Iml from C. imperialis (McIntosh et al., 1994), compared to five residues in the other a-conotoxins. 

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