title: Novel alpha- and omega-conotoxins from Conus striatus venom.
abstract: Three neurotoxic peptides from the venom of Conus striatus have been purified, biochemically characterized, and chemically synthesized. One of these, an acetylcholine receptor blocker designated alpha-conotoxin SII, has the sequence GCCCNPACGPNYGCGTSCS. In contrast to all other alpha-conotoxins, SII has three disulfide bonds (instead of two), has no net positive charge, and has a free C-terminus. The other two paralytic peptides are Ca channel-targeted omega-conotoxins, SVIA and SVIB. omega-SVIA is the smallest natural omega-conotoxin so far characterized and has the sequence CRSSGSPCGVTSICCGRCYRGKCT-NH2. Although omega-conotoxin SVIA is a potent paralytic toxic in lower vertebrate species, it was much less effective in mammals. The third toxin, omega-conotoxin SVIB, has the sequence CKLKGQSCRKTSYDCCSGSCGRSGKC-NH2. This peptide has a different pharmacological specificity from other omega-conotoxins previously purified from Conus venoms; only omega-conotoxin SVIB has proven to be lethal to mice upon ic injection. Binding competition experiments with rat brain synaptosomal membranes indicate that the high-affinity binding site for omega-conotoxin SVIB is distinct from the high-affinity omega-conotoxin GVIA or MVIIA site.
authors.affiliation: Marine Science Institute, University of Philippines, Diliman, Quezon City.
authors.forename: C A
authors.initials: CA
authors.lastname: Ramilo
authors.forename: G C
authors.initials: GC
authors.lastname: Zafaralla
authors.forename: L
authors.initials: L
authors.lastname: Nadasdi
authors.forename: L G
authors.initials: LG
authors.lastname: Hammerland
authors.forename: D
authors.initials: D
authors.lastname: Yoshikami
authors.forename: W R
authors.initials: WR
authors.lastname: Gray
authors.forename: R
authors.initials: R
authors.lastname: Kristipati
authors.forename: J
authors.initials: J
authors.lastname: Ramachandran
authors.forename: G
authors.initials: G
authors.lastname: Miljanich
authors.forename: B M
authors.initials: BM
authors.lastname: Olivera
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D002038:Bungarotoxins / Q000378:metabolism; D020916:Conotoxins; D051379:Mice; D008969:Molecular Sequence Data; D008978:Mollusk Venoms / Q000737:chemistry*; D009469:Neuromuscular Junction / Q000502:physiology; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D011894:Rana pipiens; D051381:Rats; D011950:Receptors, Cholinergic / Q000502:physiology; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013570:Synaptic Membranes / Q000378:metabolism; D020960:omega-Conotoxins
chemical_list: D002038:Bungarotoxins; D020916:Conotoxins; D008978:Mollusk Venoms; D010455:Peptides; D011950:Receptors, Cholinergic; D020960:omega-Conotoxins; C077381:omega-conotoxin SVIA; C077380:omega-conotoxin SVIB; C077379:alpha-conotoxin SII