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Glutamine-linked and non-consensus asparagine-linked oligosaccharides present in human recombinant antibodies define novel protein glycosylation motifs

Valliere-Douglass, J.F.; Eakin, C.M.; Wallace, A.; Ketchem, R.R.; Wang, W.; Treuheit, M.J.; Balland, A.

Journal of Biological Chemistry 285(21): 16012-16022

2010


ISSN/ISBN: 0021-9258
PMID: 20233717
DOI: 10.1074/jbc.m109.096412
Accession: 053426385

We report the presence of oligosaccharide structures on a glutamine residue present in the V(L) domain sequence of a recombinant human IgG2 molecule. Residue Gln-106, present in the QGT sequence following the rule of an asparagine-linked consensus motif, was modified with biantennary fucosylated oligosaccharide structures. In addition to the glycosylated glutamine, analysis of a lectin-enriched antibody population showed that 4 asparagine residues: heavy chain Asn-162, Asn-360, and light chain Asn-164, both of which are present in the IgG1 and IgG2 constant domain sequences, and Asn-35, which was present in CDR(L)1, were also modified with oligosaccharide structures at low levels. The primary sequences around these modified residues do not adhere to the N-linked consensus sequon, NX(S/T). Modeling of these residues from known antibody crystal structures and sequence homology comparison indicates that non-consensus glycosylation occurs on Asn residues in the context of a reverse consensus motif (S/T)XN located on highly flexile turns within 3 residues of a conformational change. Taken together our results indicate that protein glycosylation is governed by more diversified requirements than previously appreciated.

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