title: Functional role of EF-hands 3 and 4 in membrane-binding of KChIP1.
abstract: The aim of the present study is to explore whether membrane targeting of K+ channel-interacting protein 1 (KChIP1) is associated with its EF-hand motifs and varies with specific phospholipids. Truncated KChIP1, in which the EFhands 3 and 4 were deleted, retained the alpha-helix structure, indicating that the N-terminal half of KChIP1 could fold appropriately. Compared with wild-type KChIP1, truncated KChIP1 exhibited lower lipid-binding capability. Compared with wild-type KChIP1, increasing membrane permeability by the use of digitonin caused a marked loss of truncated KChIP1, suggesting that intact EF-hands 3 and 4 were crucial for the anchorage of KChIP1 on membrane. KChIP1 showed a higher binding capability with phosphatidylserine (PS) than truncated KChIP1. Unlike that of truncated KChIP1, the binding of wild-type KChIP1 with membrane was enhanced by increasing the PS content. Moreover, the binding of KChIP1 with phospholipid vesicles induced a change in the structure of KChIP1 in the presence of PS. Taken together, our data suggest that EF-hands 3 and 4 of KChIP1 are functionally involved in a specific association with PS on the membrane.
authors: Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors: Yan-Shun
authors: YS
authors: Liao
authors: Ku-Chung
authors: KC
authors: Chen
authors: Long-Sen
authors: LS
authors: Chang
mesh_terms: D020816:Amino Acid Motifs; D002462:Cell Membrane / Q000378:metabolism; D004072:Digitonin / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051605:Kv Channel-Interacting Proteins / Q000737:chemistry* / Q000502:physiology*; D008055:Lipids / Q000737:chemistry; D010539:Permeability; D010718:Phosphatidylserines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: C496750:KCNIP1 protein, human; D051605:Kv Channel-Interacting Proteins; D008055:Lipids; D010718:Phosphatidylserines; D010743:Phospholipids; D011994:Recombinant Proteins; D004072:Digitonin