Site-specific N-glycosylation of chicken serum IgG.
Avian serum immunoglobulin (IgG or IgY) is functionally equivalent to mammalian IgG but has one additional constant region domain (CH2) in its heavy (H) chain. In chicken IgG, each H-chain contains two potential N-glycosylation sites located on CH2 and CH3 domains. To clarify characteristics of N-glycosylation on avian IgG, we analyze N-glycans from chicken serum IgG by derivatization with 2-aminopyridine (PA) and identified by HPLC and MALDI-TOF-MS. There were two types of N-glycans: (1) high-mannose-type oligosaccharides (monoglucosylated 26.8%, others 10.5%) and (2) biantennary complex-type oligosaccharides (neutral, 29.9%; monosialyl, 29.3%; disialyl, 3.7%) on molar basis of total N-glycans. To investigate the site-specific localization of different N-glycans, chicken serum IgG was digested with papain and separated into Fab [containing variable regions (VH + VL) + CH1 + CL] and Fc (containing CH3 + CH4) fragments. Con A stained only Fc (CH3 + CH4) and RCA-I stained only Fab fractions, suggesting that high-mannose-type oligosaccharides were located on Fc (CH3 + CH4) fragments, and variable regions of Fab contains complex-type N-glycans. MS analysis of chicken IgG-glycopeptides revealed that chicken CH3 domain (structurally equivalent to mammalian CH2 domain) contained only high-mannose-type oligosaccharides, whereas chicken CH2 domain contained only complex-type N-glycans. The N-glycosylation pattern on avian IgG is more analogous to that in mammalian IgE than IgG, presumably reflecting the structural similarity to mammalian IgE.
Suzuki
Noriko
N
Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA. nrsuzuki@jhu.edu
Lee
Yuan C
YC
D000595:Amino Acid Sequence; D000818:Animals; D002240:Carbohydrate Sequence; D002417:Cattle; D002645:Chickens / Q000276:immunology*; D002851:Chromatography, High Pressure Liquid; D006020:Glycopeptides / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007074:Immunoglobulin G / Q000097:blood* / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D006020:Glycopeptides; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D009844:Oligosaccharides; D006026:Glycoside Hydrolases