title: Site-specific N-glycosylation of chicken serum IgG.
abstract: 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.
authors.affiliation: Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA. nrsuzuki@jhu.edu
authors.forename: Noriko
authors.initials: N
authors.lastname: Suzuki
authors.forename: Yuan C
authors.initials: YC
authors.lastname: Lee
mesh_terms: 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
chemical_list: D006020:Glycopeptides; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D009844:Oligosaccharides; D006026:Glycoside Hydrolases