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Identification and characterization of site‐specific N‐glycosylation in the potassium channel Kv3.1b

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Journal of Cellular Physiology

Published online on


The potassium ion channel Kv3.1b is a member of a family of voltage‐gated ion channels that are glycosylated in their mature form. In the present study, we demonstrate the impact of N‐glycosylation at specific asparagine residues on the trafficking of the Kv3.1b protein. Large quantities of asparagine 229 (N229)‐glycosylated Kv3.1b reached the plasma membrane, whereas N220‐glycosylated and unglycosylated Kv3.1b were mainly retained in the endoplasmic reticulum (ER). These ER‐retained Kv3.1b proteins were susceptible to degradation, when co‐expressed with calnexin, whereas Kv3.1b pools located at the plasma membrane were resistant. Mass spectrometry analysis revealed a complex type Hex3HexNAc4Fuc1 glycan as the major glycan component of the N229‐glycosylated Kv3.1b protein, as opposed to a high‐mannose type Man8GlcNAc2 glycan for N220‐glycosylated Kv3.1b. Taken together, these results suggest that trafficking‐dependent roles of the Kv3.1b potassium channel are dependent on N229 site‐specific glycosylation and N‐glycan structure, and operate through a mechanism whereby specific N‐glycan structures regulate cell surface expression. Site‐specific N‐glycosylation and N‐glycan structure regulate cell surface trafficking and expression of the Kv3.1b potassium channel. Mass spectrometry analysis identified Man8GlcNAc2 (high‐mannose type) and Hex3HexNAc4Fuc1 (complex type) as the glycan moieties on N220 and N229.