PMID: PMC4256492-1-5

 

    Legend: Gene, Sites

Title : The O-glycosylation Map of Lubricin

Abstract :
  1. The identified O-glycopeptides , glycan com position, fragmentation technique, annotation technique (software/manual), and glycosylation sites are listed in Table I (and in supplemental Table S1)
  2. Regions of glycosylation sites identified via CID and ETD both before and after partial de-glycosylation are shown in Fig. 4A
  3. The identified O-glycopeptides characterized 168 glycosylation sites
  4. This indicated that 63% of the identified Ser/Thr residues (266 Ser/Thr , both glycosylated and non-glycosylated, were identified) in lubricin were O-glycan modified (Fig. 4B) with a bias toward Thr glycosylation due to the high Thr content (supplemental Fig
  5. S2)
  6. An extended STP-rich region was also apparent spanning amino acids 232–1056, larger than the previously defined mucin-like domain suggested in UniProt
  7. The entire lubricin molecule has in total 370 potential O-glycosylation sites
  8. Of these, 35% of Ser/Thr (130 glycans) were HexNAc (GalNAc) modified with a distribution throughout the extensively glycosylated STP-rich region (Fig. 4B)
  9. Core 1 modified (43%, 161 glycans) and larger core 2 modified (23%, 85 glycans) glycopeptides were also identified (Fig. 4B)
  10. The high-abundant core 1 modified Ser/Thr were uniformly distributed throughout the STP-rich region , whereas the low-abundant core 2 modified residues were limited to the previously defined mucin-like domain (aa 348–856) (Fig. 4B)
  11. This was likely because the accumulative nature of glycopeptides from the repeat region made them easier to detect, and it might not necessarily be a reflection of core 2 enrichment in the repeat area
  12. Outside the STP region , only a single GalNAc-modified Thr (1159NGTLVAFR1166) was identified
  13. This residue , in the hemopexin 1 domain (1148–1191), was also shown to be glycosylated with core 2 structures (Figs. 4A and 4B; supplemental Fig
  14. S1; supplemental Table S2)
  15. The identification of core 2 glycopeptides confirmed the presence of core 2 structures on lubricin
  16. The identification of core 2 together with single HexNAc (GalNAc)-modified glycopeptides suggested that lubricin glycosylation might also have other roles in addition to lubrication
  17. The majority of the GalNAc extended into either core 1 or core 2 sialylated structures (73 glycans; Fig. 4B)
  18. Both mono- and disialylated core 1 and core 2 modified Ser/Thr were identified (Table I and supplemental Table S1), but monosialylation was more prevalent, which is consistent with previously identified synovial lubricin O-glycans (38)
Output (sent_index, trigger, protein, sugar, site):
  • 1. O-glycopeptides, , -, -, O-glycopeptides
  • 1. glycosylation, , -, -, sites
  • 11. glycopeptides, , -, -, glycopeptides
  • 11. glycopeptides, , -, -, region
  • 13. glycosylated, , -, -, residue
  • 15. glycopeptides, , -, -, glycopeptides
  • 16. glycopeptides, , -, -, glycopeptides
  • 2. glycosylation, , -, -, sites
  • 3. O-glycopeptides, , -, -, O-glycopeptides
  • 3. glycosylation, , -, -, sites
  • 4. glycosylated, , -, -, Ser/Thr
  • 4. non-glycosylated, , -, -, Ser/Thr
  • 7. O-glycosylation, , -, -, sites
  • 8. glycosylated, , -, -, region
  • 9. glycopeptides, , -, -, glycopeptides
Output(Part-Of) (sent_index, protein, site):
  • 10. STP, region
  • 11. -, glycopeptides
  • 12. STP, region
  • 13. hemopexin 1, domain
  • 4. lubricin, residues
  • 6. STP, region
  • 8. STP, region
*Output_Site_Fusion* (sent_index, protein, sugar, site):

 

 

Protein NCBI ID SENTENCE INDEX