title: Effective association of Kv channel-interacting proteins with Kv4 channel is mediated with their unique core peptide.
abstract: Kv channel-interacting proteins (KChIPs) and neuronal calcium sensor-1 (NCS-1) have been shown to interact with Kv4 channel alpha-subunits to regulate the expression and/or gating of these channels. Here we examine the specificity and sites of these proteins for interaction with Kv channel proteins. Immunoprecipitation and green fluorescent protein imaging show that KChIPs (but not NCS-1) effectively bind to Kv4.3 protein and localize at the plasma membrane when channel proteins are coexpressed. Analysis with chimeric proteins between KChIP2 and NCS-1 reveals that the three regions of KChIP2 (the linker between the first and second EF hands, the one between the third and fourth EF hands, and the C-terminal peptide after the fourth EF hand) are necessary and sufficient for its effective binding to Kv4.3 protein. The chimera with these three KChIP2 portions slowed inactivation and facilitated recovery from inactivation of Kv4.3 current. These results indicate that the sequence difference in these three regions between KChIPs and NCS-1 determines the specificity and affinity for interaction with Kv4 protein. Because the three identified regions surround the large hydrophobic crevice based on the NCS-1 crystal structure, this crevice may be the association site of KChIPs for the channel protein.
authors.affiliation: Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Xiaomeng
authors.initials: X
authors.lastname: Ren
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Shand
authors.forename: Koichi
authors.initials: K
authors.lastname: Takimoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006801:Humans; D015151:Immunoblotting; D051605:Kv Channel-Interacting Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051580:Neuronal Calcium-Sensor Proteins; D009479:Neuropeptides / Q000737:chemistry* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000737:chemistry*; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D017386:Sequence Homology, Amino Acid; D051672:Shal Potassium Channels; D013997:Time Factors
chemical_list: D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; C497021:KCND3 protein, human; C496752:KCNIP2 protein, human; C497023:Kcnd3 protein, rat; C496758:Kcnip2 protein, rat; D051605:Kv Channel-Interacting Proteins; D008164:Luminescent Proteins; D051580:Neuronal Calcium-Sensor Proteins; D009479:Neuropeptides; D010455:Peptides; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051672:Shal Potassium Channels; C101464:frequenin calcium sensor proteins; D049452:Green Fluorescent Proteins