Multiple oligosaccharide chains in the voltage-sensitive Na channel from electrophorus electricus: evidence for alpha-2,8-linked polysialic acid.
Carbohydrate substituents on the large peptide of the voltage-sensitive Na channel from Electrophorus electricus electroplax have been partially characterized by their sensitivity to endoglycosidases H and F, peptide:N-glycosidase F, Endo-N-acetylneuraminidase, and to neuraminidase. The results suggest the presence of at least two classes of oligosaccharides: neutral, high mannose or hybrid oligosaccharides, and acidic, complex oligosaccharides with a core-structure terminating in an unbranched homopolymer of sialosyl units in alpha-2,8 linkages (much greater than 5 tandem sialic acids). Large decreases in apparent Mr produced by sialidase treatments suggest an extended carbohydrate structure that could inhibit protein-protein interaction. Polysialic acid was formerly proposed to be a unique constituent of neural cell adhesion molecules (N-CAMs) in vertebrates. However, ratios of sialic acid to galactose reported for mammalian brain and muscle Na channels suggest they may also carry this oligosaccharide.
D000818:Animals; D004557:Electric Organ / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004593:Electrophorus; D006020:Glycopeptides / Q000302:isolation & purification; D006026:Glycoside Hydrolases; D007473:Ion Channels / Q000032:analysis; D008565:Membrane Proteins / Q000302:isolation & purification; D008970:Molecular Weight; D009844:Oligosaccharides / Q000302:isolation & purification*; D011134:Polysaccharides / Q000302:isolation & purification*; D012794:Sialic Acids / Q000302:isolation & purification*; D015222:Sodium Channels
D006020:Glycopeptides; D007473:Ion Channels; D008565:Membrane Proteins; D009844:Oligosaccharides; D011134:Polysaccharides; D012794:Sialic Acids; D015222:Sodium Channels; C021319:polysialic acid; D006026:Glycoside Hydrolases