title: BmKK4, a novel toxin from the venom of Asian scorpion Buthus martensi Karsch, inhibits potassium currents in rat hippocampal neurons in vitro.
abstract: A novel short-chain peptide BmKK4 was isolated from the venom of Asian scorpion Buthus martensi Karsch. It is composed of 30 amino acids including six cysteine residues, and shares less than 25% sequence identity with the known alpha-KTx toxins. The action of BmKK4 on voltage-dependent potassium currents was examined in acutely dissociated hippocampal neurons of rat. BmKK4 (10-100 microM) inhibited both the delayed rectifier and fast transient potassium current in concentration-dependent manners. The inhibition was reversible and voltage-independent. BmKK4 caused a depolarizing shift (about 10 mV) of the steady-state activation curve of the currents, without changing their steady-state inactivation behavior. The unique amino acid sequence and electrophysiological effects suggest that BmKK4 represent a new subfamily of potassium channel toxins.
authors.affiliation: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203, People's Republic of China.
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Li
authors.forename: Nai-Xia
authors.initials: NX
authors.lastname: Zhang
authors.forename: Xue-Qin
authors.initials: XQ
authors.lastname: Chen
authors.forename: Gong
authors.initials: G
authors.lastname: Wu
authors.forename: Hou-Ming
authors.initials: HM
authors.lastname: Wu
authors.forename: Guo-Yuan
authors.initials: GY
authors.lastname: Hu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012604:Scorpion Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity*; D012605:Scorpions; D016415:Sequence Alignment
chemical_list: C445369:KK toxin, Buthus martensi; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms