PMID: PMC4739677-2-8

 

    Legend: Gene, Sites

Title : General Remarks on Immunoglobulin O-glycoproteomics

Abstract :
  1. Another O-glycosylated protein that could not be identified in our study is Ig α-1 ( IgA1 )
  2. IgA1 is a high abundant human blood plasma glycoprotein that features a cluster of three to five mucin-type O-glycans in the hinge region of the heavy chain (81)
  3. This cluster harbors many prolines , hence corresponding Proteinase K generated peptides might have been not unambiguously identified (the tryptic IgA1 hinge region O-glycopeptide looks as follows: (K)89HYTNPSQDVTVPCPVPTPPTPPTPPTPPCCHPR126)
  4. Furthermore, because of the densely clustered O-glycans a potential IgA1 O-glycopeptide carrying mucin-type O-glycans at each potential site , such as PTPPTPPTPPTPPCC, might be too hydrophilic and consequently might have been among the (glyco) peptides present in the late eluting HILIC wash fraction
  5. Worth mentioning, in our study we could detect the IgA1 peptide 95QDVTVPCPVP105 in its nonglycosylated form (HILIC Fraction #11, CID, supplemental Table S2)
  6. Therefore, the O-glycosylation site S105 seems to be only partially occupied
  7. Surprisingly, human IgA1 O-glycopeptides have not been identified in any other large-scale glycoproteomic studies (30, 58, 60, 76, 77, 82)
  8. However, there is a targeted glycoproteomic study from Takahashi et al. focusing on IgA1 O-glycosylation (81)
  9. In this study the authors analyzed human plasma derived IgA1 O-glycopeptides (tryptic and nontryptic) with ESI-FT-ICR-MS/MS as well as ESI-LTQ-FT-MS/MS, both in online- and offline-Mode
  10. To pinpoint the O-glycosylation sites the authors have employed activated ion-electron capture dissociation (AI- ECD ) and ETD
  11. Another immunoglobulin that is reported to carry mucin-type O-glycans in the hinge region is Ig delta ( IgD ) (83)
  12. The plasma concentration of IgD is much lower than the concentration of IgA , IgG , and IgM but higher than that of IgE ( IgD represents 0.25% of total plasma immunoglobulins)
  13. Apart from the study conducted by Takayasu et al. from 1982 (83) on truncated O-glycopeptides (peptide\+GalNAc) at present no O-glycoproteomic data do exist for intact human IgD O-glycopeptides
  14. Also of particular interest is a recent finding by Plomp et al.: using a targeted glycoproteomics approach these authors could demonstrate, for the first time, that IgG3 is partially O-glycosylated in its hinge region (mucin-type core-1 O-glycans) (84)
Output (sent_index, trigger, protein, sugar, site):
  • 1. O-glycosylated, , protein, -, -
  • 10. O-glycosylation, , -, -, sites
  • 13. O-glycopeptides, , -, -, O-glycopeptides
  • 14. O-glycosylated, , IgG3, -, region
  • 2. glycoprotein, , IgA1, -, -
  • 2. glycoprotein, , glycoprotein, -, -
  • 3. O-glycopeptide, , -, -, region O-glycopeptide
  • 4. O-glycopeptide, , -, -, O-glycopeptide
  • 6. O-glycosylation, , -, -, site
  • 7. O-glycopeptides, , -, -, O-glycopeptides
  • 9. O-glycopeptides, , -, -, O-glycopeptides
Output(Part-Of) (sent_index, protein, site):
  • 13. IgD, O-glycopeptides
  • 3. IgA1, region O-glycopeptide
  • 3. Proteinase K, peptides
  • 4. IgA1, O-glycopeptide
  • 7. IgA1, O-glycopeptides
  • 9. IgA1, O-glycopeptides
*Output_Site_Fusion* (sent_index, protein, sugar, site):

 

 

Protein NCBI ID SENTENCE INDEX