title: mr1e, a conotoxin from Conus marmoreus with a novel disulfide pattern.
abstract: Conotoxins are well known for their highly variable structures and functions. Here we report the identification of a novel conotoxin named mr1e from Conus marmoreus. mr1e is composed of 11 amino acid residues cross-linked by two disulfide bonds (CCHSSWCKHLC). The spacing of intercysteine loops in mr1e is exactly the same as that in alpha4/3 conotoxins. However, the native mr1e peptide co-eluted on reverse-phase HPLC with the regioselectively synthesized ribbon disulfide linkage isomer (C1-C4, C2-C3) but not the globular linkage isomer (C1-C3, C2-C4). Although this peptide has the same disulfide connectivity as the chi-conotoxins, their sequences do not share significant homology. Thus, mr1e could be defined as a novel conotoxin family. By intracranial injection into mice, mr1e showed an excitatory effect. The characterization of mr1e certainly enriches our understanding of conotoxins, and also opens an avenue for further structural and functional investigation.
authors.affiliation: Institute of Protein Research, Tongji University, Shanghai 200092, China.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Shao
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Sumin
authors.initials: S
authors.lastname: Wang
authors.forename: Chengwu
authors.initials: C
authors.lastname: Chi
authors.forename: Chunguang
authors.initials: C
authors.lastname: Wang
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects* / Q000502:physiology*; D020916:Conotoxins / Q000008:administration & dosage* / Q000737:chemistry*; D052078:Conus Snail / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D008297:Male; D051379:Mice
chemical_list: D020916:Conotoxins; D003432:Cross-Linking Reagents; D004220:Disulfides