Potassium channel-interacting protein 1 (KChIP1), a Ca<sup>2+</sup> sensor protein, regulates the function of A-type Kv4 potassium channels and increases their cell surface expression. Myristoylation at the N-terminus of KChIP1 has been suggested to facilitate membrane-binding, but was not sufficient for stable membrane assaociation. The aim of the present study is to investigate whether EF-hand motifs of KChIP1 are crucial for membranal targeting in addition to the N-terminal myristoyl group, and how the membrane association of KChIP1 is influenced by lipid compositions. According to hydropathy profile, EF-hands 3 and 4 of KChIP1 showed highly hydrophobicity. After deleting EF-hands 3 and 4, the altered microenvironment of Trp residue and decreased hydrophobicity were found in truncated KChIP1, but it still maintained £\-helix structure. Furthermore, truncated KChIP1 exhibited lower lipid-binding ability, affecting intracellular membrane localization and was almost diminished underlying increasing membrane permeability by digitonin in cells, suggesting that intact EF-hands 3 and 4 may be related to the anchorage of KChIP1 on cellular membrane. KChIP1, but not mutant, specifically bound with phosphatidylserine by lipid binding assay and the FTIR spectra showed the change of £\-helix structure by binding lipid large unilamellar vesicles was dependent on phosphatidylserine. Either phosphatidylserine or potassium channels enhanced KChIP1 to form tetramer for targeting to phospholipids by using chemical cross-linking assay. Taken together, our data highly suggest that intact of EF-hands 3 and 4 should structurally and functionally involve in fulfilling the physiological activity of KChIP1.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0715108-124010 |
| Date | 15 July 2008 |
| Creators | Liao, Yen-Shun |
| Contributors | Chun-Chang Chang, Wen-Chun Hung, Long-Sen Chang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715108-124010 |
| Rights | withheld, Copyright information available at source archive |
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