N-linked glycoproteins associated with flagellar scales in a flagellate green alga: characterization of interactions.
Glycoproteins associated with one type of flagellar scale (p-scale) isolated from the flagellate green alga Tetraselmis striata (Prasinophyceae) were shown to bind the mannose-specific lectin GNA (Galanthus nivalis agglutinin). Enzymatic deglycosylation of the glycoproteins with N-glycosidase F led to an electrophoretic mobility shift to lower molecular masses in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and abolished GNA-binding strongly indicating that most of the scale-associated glycoproteins contain asparagine-linked oligosaccharide side chains presumably of the high mannose type. To evaluate the significance of N-linked glycoproteins for scale structure and integrity, p-scales were digested with various proteases or extracted with 8 M urea and their ultrastructure and protein composition determined. The results show that while scale-associated N-linked glycoproteins do not determine the overall structure of the scale subunits (which consist of complex polysaccharides), they are apparently involved in mediating linkages between scale subunits; we have tentatively identified one glycoprotein of Mr 280,000 which may link outer scale subunits to one another. In addition, some scale-associated N-linked glycoproteins may provide connections between the layer of p-scales and the underlying flagellar membrane.
Becker
D
D
Botanisches Institut, Lehrstuhl I, Universität zu Köln, Köln/Deutschland.
Melkonian
M
M
D000460:Chlorophyta / Q000737:chemistry* / Q000648:ultrastructure; D005407:Flagella / Q000737:chemistry* / Q000648:ultrastructure; D027801:Galanthus; D006023:Glycoproteins / Q000737:chemistry* / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000494:pharmacology; D037102:Lectins / Q000378:metabolism; D008854:Microscopy, Electron; D009844:Oligosaccharides / Q000737:chemistry; D037121:Plant Lectins; D012697:Serine Endopeptidases / Q000494:pharmacology; D012995:Solubility; D013381:Subtilisins / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology
D006023:Glycoproteins; D037102:Lectins; D009844:Oligosaccharides; D037121:Plant Lectins; D014508:Urea; D006026:Glycoside Hydrolases; D012697:Serine Endopeptidases; D013381:Subtilisins; C028344:glutamyl endopeptidase