Title : O-glycosylation in hinge
region of mouse
immunoglobulin G2b
Abstract :
- Mouse monoclonal immunoglobulin G2b ( IgG2b ) antibodies are known to contain two forms of the heavy chain that are different in susceptibility to the protease attack
- In the present study, by use of an affinity column containing sialic acid-binding lectins from Maackia amurensis seeds, a mouse monoclonal IgG2b was successfully separated into three phenotypes, which are different in the degree of sialylation in the heavy chain
- In the N-linked oligosaccharides from all of the IgG2b phenotypes, virtually no sialylation was detected
- Elution profiles of the lysyl endopeptidase digestion products were compared for the three phenotypes
- The peptides eluted at different retention times were subjected to fast atom bombardment-mass spectrometry and amino acid sequence analyses
- It was revealed that approximately 40% of the heavy chain of the mouse IgG2b are O-glycosylated at Thr-221A in the hinge region , predominantly with a tetrasaccharide composed of GalNAc, Gal, and two N-glycolylneuraminic acid residues.
- We suggest that the O-glycosylation renders the hinge region resistant against the proteolyses of the heavy chain
- A therapeutic significance of the O-glycosylation of IgG2b is briefly discussed