N-linked glycosylation of ether á go-go potassium channels: effects on cell surface expression and functional properties

摘要: Ether a go-go (Eag1) is voltage gated potassium channel, apparently involved in broad variety of cellular events. Results from this work show that rat tissues the Eag1 protein predominantly expressed brain tissue where it undergoes N-linked glycosylation, cotranslational modification known to affect biogenesis and functional properties numerous plasma membrane proteins. Analogously, human glycosylation when heterologous systems.The Eag1, as CHO cells, natively brain, each exist two isoforms, which harbor different asparagine-linked oligosaccharides. Examination carbohydrate attachments with endoglycosidases revealed distinct complexes, core-oligosaccharide complex-oligosaccharide, contribute molecular masses hEag1 isoforms 2-5 kDa 20-25 kDa, respectively. Mutation asparagine residues six putative motifs (N-X-S/T), Asn 388 Asn406 altered channels. However, single amino acid exchanges four remaining had no effect on glycosylation.Asparagine site attachment core-oligosaccharide, sensitive Endoglycosidase H recognisable by Concanavalin A. significant intracellular localisation channels, although interference some other unidentified function cannot be excluded. Asparagine 406 carries resistant unrecognisable The complex-oligosaccharide seems have an important complex since mutation results phenotype. Intracellular distribution lacking strongly affected, showing complex-perinuclear instead widespread staining pattern. This case also for mutant both sites. Immunofluorescence experiments indicate channel prot eins complex-oligosaccharides are, at least partially, trapped endoplasmatic reticulum. can explained, e.g., folding problems due loss oligosaccharide attachment. unglycosylated solely core-glycosylated not likely introduced mutation, same was obtained expression wild-type deficient cells. Although partially reticulum, populations channels must cell surface, currents are detectable cells expressing albeit reduced amplitude. Loss core -oligosaccharide only has current amplitude.Furthermore, shift voltage-dependence towards more positive potentials, phenomenon commonly observed desialylation voltage-dependent sodium Additionally PIAS1 identified interaction partner C-terminus independent Yeast-Two-Hybrid screens. nuclei acts inhibitor STAT mediated gene-activation. hypothesis protein, or part it, functionally interact nuclear controversial, recently evidence such interactions accumulating. particular interest given its involvement cancer.