title: Evidence showing an intermolecular interaction between KChIP proteins and Taiwan cobra cardiotoxins.
abstract: Direct protein-protein interaction between Taiwan cobra cardiotoxin3 (CTX3) and potassium channel-interacting proteins (KChIPs) was investigated in the present study. It was found that KChIPs bound with CTX3, in which KChIP and CTX3 formed a 1:1 complex as evidenced by the results of chemical cross-linking. Pull-down assay revealed that the intact EF-hands 3 and 4 of KChIP1 were critical for CTX3-binding. Likewise, removal of EF-hands 3 and 4 distorted the ability of KChIP1 to bind with Kv4.2 N-terminal fragment (KvN) as well as fluorescent probe 8-anilinonaphthalene-1-sulfonate (ANS). In contrast to the interaction between KChIP1 and KvN, the binding of CTX3 to KChIP1 showed a Ca(2+)-independent manner. Fluorescence measurement revealed that CTX3 affected the binding of ANS to Ca(2+)-bound KChIP1, but not Ca(2+)-free KChIP1. Alternatively, KChIP1 simultaneously bound with KvN and CTX3, and the interaction between KChIP1 and KvN was enhanced by CTX3. In terms of the fact that KChIPs regulate the electrophysiological properties of Kv K(+) channel, the potentiality of CTX for this biomedical application could be considered.
authors.affiliation: Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC.
authors.forename: Ya-Ling
authors.initials: YL
authors.lastname: Lin
authors.forename: Shinne-Ren
authors.initials: SR
authors.lastname: Lin
authors.forename: Tony T
authors.initials: TT
authors.lastname: Wu
authors.forename: Long-Sen
authors.initials: LS
authors.lastname: Chang
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry / Q000378:metabolism*; D017815:Elapidae; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D051605:Kv Channel-Interacting Proteins; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated; D011485:Protein Binding; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D051672:Shal Potassium Channels; D013624:Taiwan
chemical_list: D002135:Calcium-Binding Proteins; D004179:Cobra Cardiotoxin Proteins; D005456:Fluorescent Dyes; C497018:KCND2 protein, human; C496750:KCNIP1 protein, human; C496749:KCNIP3 protein, human; C496753:KCNIP4 protein, human; D051605:Kv Channel-Interacting Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D051672:Shal Potassium Channels; D002118:Calcium