Palmitoylation of KChIP splicing variants is required for efficient cell surface expression of Kv4.3 channels.
The Ca(2+)-binding proteins KChIP1-4 (KChIP3 is also known as DREAM and calsenilin) act as auxiliary subunits for voltage-gated K(+) channels in the Kv4 family. Here we identify three splicing isoforms of rat KChIP2 with variable N-terminal peptides. The two longer isoforms, which contain the 32-amino acid peptide, produce larger increases in Kv4.3 protein level and current density and more effectively localize themselves and their associated channels at the plasma membrane than the shortest variant. The 32-amino acid peptide contains potential palmitoylation cysteines. Metabolic labeling demonstrates that these cysteines in the KChIP2 isoforms, as well as the corresponding sites in KChIP3, are palmitoylated. Mutating these cysteines reduces their plasma membrane localization and the enhancement of Kv4.3 current density. Thus, palmitoylation of the KChIP auxiliary subunits controls plasma membrane localization of their associated channels.
Takimoto
Koichi
K
Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, 3343 Forbes Avenue, Pittsburgh, PA 15260, USA. koichi@pitt.edu
Yang
Eun-Kyoung
EK
Conforti
Laura
L
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D003545:Cysteine / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D015151:Immunoblotting; D007700:Kinetics; D051605:Kv Channel-Interacting Proteins; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D010169:Palmitic Acids / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms; D051381:Rats; D013997:Time Factors; D014018:Tissue Distribution
D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; C496758:Kcnip2 protein, rat; D051605:Kv Channel-Interacting Proteins; D010169:Palmitic Acids; D010455:Peptides; D015221:Potassium Channels; D020033:Protein Isoforms; D003545:Cysteine