Title : A comparative study of the N-linked oligosaccharide structures of human IgG subclass proteins
Abstract :
Quantitative oligosaccharide profiles were determined for each of 18 human IgG paraproteins representing the four subclasses
Each para protein exhibits a unique profile that may be substantially different from that observed for polyclonal IgG
The IgG2 and some IgG3 proteins analysed exhibit a predominance of oligosaccharide moieties having galactose on the Man(alpha 1----3) arm rather than the Man(alpha 1----6) arm; it was previously held that galactosylation of the Man(alpha 1----6) arm is preferred, as observed for IgG1 , IgG4 and polyclonal IgG
An IgG4 protein is reported that has galactosylated Man(alpha 1----3) and Man(alpha 1----6) arms on both Fc-localized carbohydrate moieties; previous findings suggested that such fully glycosylated structures could not be accommodated within the internal space of the C gamma 2 domains
Unusual monoantennary oligosaccharides present in IgG2 and IgG3 proteins were isolated and their structures determined