title: Structure-function relationship of bifunctional scorpion toxin BmBKTx1.
abstract: As the first identified scorpion toxin active on both big conductance Ca2+-activated K+ channels (BK) and small conductance Ca2+-activated K+ channels (SK), BmBKTx1 has been proposed to have two separate functional faces for two targets. To investigate this hypothesis, two double mutants, K21A-Y30A and R9A-K11A, together with wild-type toxin were expressed in Escherichia coli. The recombinant toxins were tested on cockroach BK and rat SK2 channel for functional assay. Mutant K21A-Y30A had a dramatic loss of function on BK but retained its function on SK. Mutant R9A-K11A did not lose function on BK or SK. These data support the two functional-face hypothesis and indicate that the BK face is on the C-terminal beta-sheet.
authors.affiliation: School of Life Sciences, University of Science and Technology of China, Hefei, China.
authors.forename: Suming
authors.initials: S
authors.lastname: Wang
authors.forename: Lijun
authors.initials: L
authors.lastname: Huang
authors.forename: Dieter
authors.initials: D
authors.lastname: Wicher
authors.forename: Chengwu
authors.initials: C
authors.lastname: Chi
authors.forename: Chenqi
authors.initials: C
authors.lastname: Xu
mesh_terms: D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics; D009154:Mutation; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D012604:Scorpion Venoms / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: C490373:BKTx1 protein, Buthus martensi; D024681:Potassium Channels, Calcium-Activated; D011994:Recombinant Proteins; D012604:Scorpion Venoms