title: Two novel ergtoxins, blockers of K+-channels, purified from the Mexican scorpion Centruroides elegans elegans.
abstract: Voltage-gated potassium channels of the ether-a-go-go related gene (ERG) family are implicated in many important cellular processes. Three such genes have been cloned (erg1, erg2 and erg3) and shown to be expressed in the central nervous system (CNS) of mammalians. This communication describes the isolation and characterization of two isoforms of scorpion toxin (CeErg4 and CeErg5, systematic nomenclature gamma-KTx1.7 and gamma-KTx1.8, respectively) that can discriminate the various subtypes of ERG channels of human and rat. These peptides were purified from the venom of the Mexican scorpion Centruroides elegans elegans. They contain 42 amino acid residues, tightly folded by four disulfide bridges. Both peptides block in a reversible manner human and rat ERG1 channels, but have no effect on human ERG2. They also block completely and irreversibly the rat ERG2 and the human ERG3 channels hence are excellent tools for the discrimination of the various sub-types of ion-channels studied.
authors.affiliation: Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Col. Chamilpa, Cuernavaca, 62210, Mexico.
authors.forename: Rita
authors.initials: R
authors.lastname: Restano-Cassulini
authors.forename: Timoteo
authors.initials: T
authors.lastname: Olamendi-Portugal
authors.forename: Fernando
authors.initials: F
authors.lastname: Zamudio
authors.forename: Baltazar
authors.initials: B
authors.lastname: Becerril
authors.forename: Lourival Domingos
authors.initials: LD
authors.lastname: Possani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000302:isolation & purification / Q000378:metabolism; D051381:Rats; D012604:Scorpion Venoms / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D012605:Scorpions / Q000737:chemistry*; D016415:Sequence Alignment
chemical_list: C035413:Centruroides toxin; D051638:Ether-A-Go-Go Potassium Channels; D010455:Peptides; D026902:Potassium Channel Blockers; D012604:Scorpion Venoms; C532645:ergtoxin 4, Centruroides elegans; C532646:ergtoxin 5, Centruroides elegans