title: Isolation and cloning of a conotoxin with a novel cysteine pattern from Conus caracteristicus.
abstract: A new conotoxin, ca16a, containing 8 cysteine residues was purified, sequenced, and cloned from a worm-hunting snail, Conus caracteristicus. This conotoxin is an extremely hydrophilic peptide comprising 34 residues, with 4 acidic and 4 basic residues. It is rich in polar Gly, Ser, and Thr residues and includes a hydroxylated Pro residue. The cysteine arrangement pattern of ca16a (-C-C-CC-C-CC-C-, designated as framework #16) is distinct from that of other known conotoxins. Furthermore, the signal peptide sequence of this conotoxin does not share any homology with those of other conotoxins. Leu residues account for almost 50% of its 20-residue signal peptide. The unique cysteine framework and signal peptide sequence of ca16a suggest that it belongs to a new conotoxin superfamily.
authors.affiliation: Institute of Protein Research, College of Life Sciences and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China.
authors.forename: Duo-Duo
authors.initials: DD
authors.lastname: Yuan
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Shao
authors.forename: Can
authors.initials: C
authors.lastname: Peng
authors.forename: Cheng-Wu
authors.initials: CW
authors.lastname: Chi
authors.forename: Zhan-Yun
authors.initials: ZY
authors.lastname: Guo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D020916:Conotoxins / Q000096:biosynthesis / Q000302:isolation & purification*; D052078:Conus Snail / Q000737:chemistry; D003545:Cysteine / Q000032:analysis*; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D020916:Conotoxins; D021382:Protein Sorting Signals; C532439:ca16a protein, Conus caracteristicus; D003545:Cysteine