Functional roles of EF-hands in human Potassium channel-interacting protein 2.2

Liya Lee, Ku Chung Chen, Long Sen Chang

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Single site-directed mutations at each of the four EF-hand loops of potassium channel-interacting protein 2.2 (KChIP2.2) were carried out to explore the functional roles of EF-hands in KChIP2.2. In contrast to those on EF-hands 1 and 2, mutations on EF-hands 3 or 4 distorted the high affinity Ca 2+-binding site of KChIP2.2. However, the Mg 2+-binding ability of KChIP2.2 was marginally affected by the mutations. The gross conformation of mutated KChIP2.2 was indistinguishable from wild-type KChIP2.2 as revealed by CD spectra. The results of size exclusion chromatography showed that, with exception of EF-hand 4 mutant, mutations on EF-hands 1, 2 or 3 caused KChIP2.2 to form oligomer. Pull-down assay revealed that, unlike wild-type KChIP2.2, the interaction between mutated KChIP2.2 and Kv4.2 was not notably enhanced by Ca 2+ and Mg 2+. Coexpression of Kv4.2 and KChIP2.2 in HeLa cells revealed that mutations on EF-hands did not alter the intracellular co-localization of KChIP2.2 and Kv4.2. Together with previous findings that EF-hand mutants of KChIP proteins are unable to regulate the kinetics of Kv4.2, our data show that the intact EF-hands should be crucial for the formation of active conformation of KChIP2.2 when the protein is loaded with Ca 2+ and Mg 2+.

Original languageEnglish
Pages (from-to)1081-1087
Number of pages7
JournalProtein and Peptide Letters
Volume16
Issue number9
DOIs
Publication statusPublished - Sep 2009
Externally publishedYes

Keywords

  • EF-hand mutant
  • KChIP
  • Metal-binding properties
  • Oligomerization

ASJC Scopus subject areas

  • Biochemistry
  • Structural Biology

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