title: Effects of metal-binding properties of human Kv channel-interacting proteins on their molecular structure and binding with Kv4.2 channel.
abstract: The goal of the present study is to explore whether Ca2+ and Mg2+-binding properties of isomeric Kv channel-interacting proteins (KChIPs) have different effects on their molecular structure and the binding with Kv channel. 8-Anilinonaphthalene- 1-sulfonate fluorescence measurement showed that KChIP4.1 and KChIP2.2 possessed one and two types of Ca2+-binding sites, respectively, and only one type of Mg2+-binding site was noted in the two KChIP proteins. Removal of EF-hand 4 (EF-4) caused a marked drop in their high affinities for Ca2+, but the binding affinity for Mg2+ remained mostly the same. Unlike KChIP4.1, the intact EF-4 was essential for the Kv channel-binding ability of KChIP2.2 in a metal-free buffer. Nevertheless, the interaction of wild-type KChIPs and EF-4-truncated mutants with Kv channel was enhanced by the addition of Mg2+ and Ca2+. In contrast to KChIP4.1, the thermal stability of KChIP2.2 was decreased by the binding of Mg2+ and Ca2+. These results suggest that the conformational change with metal-bound KChIP4.1 is crucial for its interaction with Kv channel but not for KChIP2.2, and that the Mg2+- and Ca2+-binding properties of KChIP2.2 and KChIP4.1 have different effects on their molecular structure.
authors.affiliation: Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Ching-Ping
authors.initials: CP
authors.lastname: Chen
authors.forename: Liya
authors.initials: L
authors.lastname: Lee
authors.forename: Long-Sen
authors.initials: LS
authors.lastname: Chang
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000737:chemistry* / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D051605:Kv Channel-Interacting Proteins / Q000378:metabolism*; D008274:Magnesium / Q000737:chemistry* / Q000494:pharmacology; D015394:Molecular Structure; D011485:Protein Binding; D051672:Shal Potassium Channels / Q000378:metabolism*; D014162:Transfection
chemical_list: C496752:KCNIP2 protein, human; D051605:Kv Channel-Interacting Proteins; D051672:Shal Potassium Channels; D008274:Magnesium; D002118:Calcium