Structural characterization of the N-glycan moiety and site of glycosylation in vitellogenin from the decapod crustacean Cherax quadricarinatus.
Glycosylation is of importance for the structure and function of proteins. In the case of vitellin (Vt), a ubiquitous protein accumulated into granules as the main yolk protein constituent of oocytes during oogenesis, glycosylation could be of importantance for the folding, processing and transport of the protein to the yolk and also provides a source of carbohydrate during embryogenesis. Vt from the crayfish Cherax quadricarinatus is synthesized as a precursor protein, vitellogenin (Vg), in the hepatopancreas, transferred to the hemolymph, and mobilized into the growing oocyte via receptor-mediated endocytosis. The gene sequence of C. quadricarinatus shows a 2584-amino-acid protein with 10 putative glycosylation sites. In this study a combined approach of lectin immunoblotting, in-gel deglycosylation, and mass spectrometry was used to identify the glycosylation sites and probe the structure of the glycan moieties using C. quadricarinatus Vg as a model system. Three of the consensus sites for N-glycosylation-namely, Asn(152), Asn(160) and Asn(2493)-were glycosylated with the high-mannose glycans, Man(5-9)GlcNAc(2), and the glucose-capped oligosaccharide Glc(1)Man(9)GlcNAc(2).
Khalaila
Isam
I
Institute for Medical Physics and Biophysics University of Münster, Robert-Koch-Str. 31 D-48149, Münster, Germany. isam.khalaila@epfl.ch
Peter-Katalinic
Jasna
J
Tsang
Clarence
C
Radcliffe
Catherine M
CM
Aflalo
Eliahu D
ED
Harvey
David J
DJ
Dwek
Raymond A
RA
Rudd
Pauline M
PM
Sagi
Amir
A
D000818:Animals; D015153:Blotting, Western; D003445:Crustacea; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D011134:Polysaccharides / Q000737:chemistry*; D011487:Protein Conformation; D021241:Spectrometry, Mass, Electrospray Ionization; D014819:Vitellogenins / Q000737:chemistry* / Q000378:metabolism
D011134:Polysaccharides; D014819:Vitellogenins