title: A novel conotoxin, qc16a, with a unique cysteine framework and folding.
abstract: A novel conotoxin, qc16a, was identified from the venom of vermivorous Conus quercinus. qc16a has only 11 amino acid residues, DCQPCGHNVCC, with a unique cysteine pattern. Its disulfide connectivity was determined to be I-IV, II-III. The NMR structure shows that qc16a adopts a ribbon conformation with a simple beta-turn motif formed by residues Gly6, His7 and Asn8. qc16a causes depression symptom in mice when injected intracranially. Point mutation results showed that Asp1, His7 and Asn8 are all essential for the activity of qc16a. Electrophysiologically, qc16a has no strong effect on the whole-cell currents of neurons and the currents of Drosophila Shaker channels, human BK channels and Na(V)1.7 channels. Its specific target still remains to be identified.
authors.affiliation: Institute of Protein Research, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Mingyu
authors.initials: M
authors.lastname: Ye
authors.forename: Jing
authors.initials: J
authors.lastname: Hong
authors.forename: Mi
authors.initials: M
authors.lastname: Zhou
authors.forename: Lijun
authors.initials: L
authors.lastname: Huang
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Shao
authors.forename: Youshan
authors.initials: Y
authors.lastname: Yang
authors.forename: Fred J
authors.initials: FJ
authors.lastname: Sigworth
authors.forename: Chengwu
authors.initials: C
authors.lastname: Chi
authors.forename: Donghai
authors.initials: D
authors.lastname: Lin
authors.forename: Chunguang
authors.initials: C
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000832:Animals, Poisonous / Q000378:metabolism / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D020916:Conotoxins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D052078:Conus Snail / Q000737:chemistry* / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D003864:Depression, Chemical; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004333:Drug Administration Routes; D004566:Electrodes; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D017354:Point Mutation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D020916:Conotoxins; D004220:Disulfides; D003545:Cysteine