Trafficking-dependent phosphorylation of Kv1.2 regulates voltage-gated potassium channel cell surface expression
| Autor: | Eliana Clark, Helene Vacher, Jae-Won Yang, Kang-Sik Park, James S. Trimmer |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Biology
Endoplasmic Reticulum complex mixtures Cell Line Cell membrane chemistry.chemical_compound Mice Phosphoserine Tandem Mass Spectrometry Chlorocebus aethiops medicine Kv1.2 Potassium Channel Homomeric Animals Humans natural sciences Phosphorylation Ion channel Multidisciplinary urogenital system Endoplasmic reticulum Cell Membrane Brain Voltage-gated potassium channel Biological Sciences Molecular biology Cell biology Rats Protein Transport medicine.anatomical_structure chemistry nervous system Cytoplasm Mutation biological phenomena cell phenomena and immunity Ion Channel Gating Chromatography Liquid |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America. 104(50) |
| ISSN: | 1091-6490 |
| Popis: | Kv1.2 α-subunits are components of low-threshold, rapidly activating voltage-gated potassium (Kv) channels in mammalian neurons. Expression and localization of Kv channels is regulated by trafficking signals encoded in their primary structure. Kv1.2 is unique in lacking strong trafficking signals and in exhibiting dramatic cell-specific differences in trafficking, which is suggestive of conditional trafficking signals. Here we show that a cluster of cytoplasmic C-terminal phosphorylation sites regulates Kv1.2 trafficking. Using tandem MS to analyze Kv1.2 purified from rat, human, and mouse brain, we identified in each sample in vivo phosphoserine (pS) phosphorylation sites at pS434, pS440, and pS441, as well as doubly phosphorylated pS440/pS441. We also found these sites, as well as pS449, on recombinant Kv1.2 expressed in heterologous cells. We found that phosphorylation at pS440/pS441 is present only on the post-endoplasmic reticulum (ER)/cell surface pool of Kv1.2 and is not detectable on newly synthesized and ER-localized Kv1.2, on which we did observe pS449 phosphorylation. Elimination of PS440/PS441 phosphorylation by mutation reduces cell-surface expression efficiency and functional expression of homomeric Kv1.2 channels. Interestingly, mutation of S449 reduces phosphorylation at pS440/pS441 and also decreases Kv1.2 cell-surface expression efficiency and functional expression. These mutations also suppress trafficking of Kv1.2/Kv1.4 heteromeric channels, suggesting that incorporation of Kv1.2 into heteromeric complexes confers conditional phosphorylation-dependent trafficking to diverse Kv channel complexes. These data support Kv1.2 phosphorylation at these clustered C-terminal sites as playing an important role in regulating trafficking of Kv1.2-containing Kv channels. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|