title: ImKTx88, a novel selective Kv1.3 channel blocker derived from the scorpion Isometrus maculates.
abstract: Scorpion toxins are useful in the structure-function research of ion channels and valuable resources for drug design. The Kv1.3 channel is an important pharmacological target for the therapy of T cell-mediated autoimmune diseases, and many toxin peptides targeting Kv1.3 have been identified as good drug candidates in recent years. In this study, a novel toxin gene ImKTx88 was isolated from the venom of the scorpion Isometrus maculates through the construction of the cDNA library method, and the recombinant toxin peptide was purified and characterized physiologically. The mature peptide of ImKTx88 contained 39 amino acid residues including six cysteines and was predicted to be a new member of α-KTx scorpion family by sequence analysis. The electrophysiological experiments further indicated that the rImKTx88 peptide had a novel pharmacological profile: it inhibited Kv1.3 channel current with an IC₅₀ of 91 ± 42 pM, and exhibited very good selectivity for Kv1.3 over Kv1.1 (4200-fold) and Kv1.2 (93000-fold) channels, respectively. All these results suggested that, as a new selective Kv1.3 channel blocker, the ImKTx88 peptide may serve as a potential drug candidate in the therapy of autoimmune diseases.
authors.affiliation: School of Medicine, Wuhan University, Wuhan 430071, People's Republic of China.
authors.forename: Song
authors.initials: S
authors.lastname: Han
authors.forename: Youtian
authors.initials: Y
authors.lastname: Hu
authors.forename: Ruhong
authors.initials: R
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Yi
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wei
authors.forename: Yingliang
authors.initials: Y
authors.lastname: Wu
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Cao
authors.forename: Wenxin
authors.initials: W
authors.lastname: Li
authors.forename: Xiaohua
authors.initials: X
authors.lastname: He
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004594:Electrophysiology; D015723:Gene Library; D057809:HEK293 Cells; D006801:Humans; D051664:Kv1.3 Potassium Channel / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D018408:Patch-Clamp Techniques; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012604:Scorpion Venoms / Q000737:chemistry* / Q000235:genetics; D012605:Scorpions / Q000235:genetics*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
chemical_list: D051664:Kv1.3 Potassium Channel; D011993:Recombinant Fusion Proteins; D012604:Scorpion Venoms