Table I. A list of the CID- and ETD-identified glycopeptides with their peptide sequence, types of glycans, position in the peptide sequence, and annotation method used.
| Lubricin peptide | Glycan compositiona | Assignmentb | Annotation | Lubricin peptide | Glycan composition | Assignment | Annotationc |
|---|---|---|---|---|---|---|---|
| K.STTK.R | 2, 3 | CID | Manual | K.KAPPSGASQTIK.S | 3, 4 | Both | Both |
| K.STTKR.S | 3 | CID | Manual | K.APPPSGASQTIK.S | 3, 4 | Both | Manual |
| R.SPKPPNKK.K | 3 | CID | Manual | K.VTTPDTSTTQHNK.V | 3 | Both | Manual |
| K.VSTSPK.I | 1, 3 | CID | Both | K.ITTAKPINPR.P | 3 | ETD | Both |
| K.ETTVETK.E | 3 | CID | Manual | K.ETSLTVNKETTVETK.E | 4 | ETD | Both |
| K.ETTTTNK.Q | 3, 4 | CID | Both | K.ETTVETKETTTTNK.Q | 3 | ETD | Both |
| K.TTSAK.E | 3, 6 | CID | Manual | K.ETTTTNKQTSTDGK.E | 3 | CID | Manual |
| K.DLAPTSK.V | 1, 2, 3, 5, 8, 10, 11 | CID | Manual | K.TTSAKETQSIEK.T | 1, 3, 4 | Both | Both |
| K.VLAKPTPK.A | 1, 3, 4 | Both | Both | K.ETQSIEKTSAK.D | 3, 4 | Both | Both |
| K.GPALTTPK.E | 1, 3, 4 | CID | Manual | K.TSAKDLAPTSK.V | 1, 3, 4, 5, 10 | Both | Both |
| K.EPTPTTPK.E | 1, 3 | CID | Manual | K.EPTPTTPKEPASTTPK.E | 3 | CID | Manual |
| K.EPASTTPK.E | 1, 3 | CID | Manual | K.EPTPTTIKSAPTTPK.E | 3, 4 | CID | Manual |
| K.EPTPTTIK.S | 1, 3, 8 | CID | Manual | K.SAPTTPKEPAPTTTK.S | 1, 3 | ETD | Both |
| K.EPAPTAPK.K | 3, 8, 10 | CID | Manual | K.EPAPTTTKEPAPTTPK.E | 3 | Both | Both |
| K.EPSPTTPK.E | 1, 3 | CID | Manual | K.EPAPTTTKEPAPTTTK.S | 3 | Both | Manual |
| K.SAPTTTK.E | 1 | CID | Manual | K.SAPTTPKEPAPTTPK.K | 1, 3 | ETD | Both |
| K.EPSPTTTK.E | 6, 8 | ETD | Both | K.EPAPTTPKEPTPTTPK.E | 3 | CID | Manual |
| K.ETAPTTPKK.L | 3 | Both | Both | K.EPTPTTPKEPAPTTK.E | 8 | CID | Manual |
| K.KLTPTTPEK.L | 1, 3 | Both | Manual | K.EPAPTTPKEPAPTAPK.K | 3 | Both | Both |
| K.LTPTTPEK.L | 3 | Both | Both | K.EPAPTTTKEPSPTTPK.E | 3 | CID | Manual |
| K.AAAPNTPK.E | 3, 4, 8, 10 | CID | Manual | K.SAPTTTKEPAPTTTK.S | 1, 3 | ETD | Both |
| K.GTAPTTLK.E | 3, 4, 8, 10 | CID | Manual | K.SAPTTPKEPSPTTTK.E | 1, 6 | ETD | Both |
| K.ELAPTTTK.E | 1, 3 | Both | Manual | a.EPAPTTPKETAPTTPK.a | 3 | ETD | Both |
| K.GTAPTTPK.E | 1, 3 | CID | Manual | K.GTAPTTLKEPAPTTPK.K | 3 | ETD | Both |
| K.GPTST TSDK.P | 1, 3 | ETD | Both | K.EPAPTTPKKPAPK.E | 3 | ETD | Manual |
| K.EPTTIHK.S | 8, 10 | CID | Manual | K.GPTSTTSDKPAPTTPK.E | 1 | ETD | Both |
| K.ALENSPK.E | 3, 4 | CID | Manual | K.ETAPTTPKEPAPTTPK.K | 3 | ETD | Both |
| K.EPGVPTTK.T | 1, 3, 4, 10 | Both | Manual | K.SPDESTPELSAEPTPK.A | 3, 4 | CID | Manual |
| K.ETATTTEK.T | 1, 3 | CID | Manual | K.ALENSPKEPGVPTTK.T | 1, 3 | Both | Manual |
| K.TTTLAPK.V | 1, 2, 3 | CID | Manual | R.TTPETTTAAPK.M | 3 | Both | Manual |
| K.VTTTK.K | 3 | CID | Manual | K.ITTLKTTTLAPK.V | 1, 3 | ETD | Manual |
| R.ATNSK.A | 3 | CID | Both | K.ITATTTQVTSTTTQDTTPFK.I | 1, 3 | ETD | Both |
| K.KPTSTK.K | 1, 3, 4 | CID | Manual | K.KPTSTKKPK.T | 1, 3, 4, 5, 8, 10 | CID | Manual |
| K.TMPR.V | 3 | CID | Manual | R.KPKTTPTPR.K | 1, 3, 8 | CID | Both |
| K.TTPTPR.K | 1, 3, 4 | CID | Manual | R.NGTLVAFR.G | 1, 6, 10 | CID | Manual |
| aa.EPAPTTPK.aa | 1, 3, 4, 8, 10 | CID | Manual | K.ETAPTTPK.K | 1, 3 | Both | Manual |
| aa.EPAPTTTK.aa | 1, 3, 8 | CID | Manual | K.EPAPTTTKSAPTTPK.E | 3 | CID | Manual |
| K.KPAPTTPK.E | 1, 3 | CID | Both | K.SAPTTPK.E | 1, 3, 8 | CID | Manual |
Notes: The line under an amino acid in a peptide sequence represents the position of glycosylation. The data showed glycosylation of threonine in the EPAPTTPK and KPAPTTPK repeats and two of the three sites in SAPTTPK and EPAPTTTK.
a 1, GalNAcα1-; 2, NeuAcα2–6GalNAcα1-; 3, Galβ1–3GalNAcα1-; 4, NeuAcα2–3Galβ1–3GalNAcα1-/NeuAcα2–6(Galβ1–3)GalNAcα1-; 5, NeuAcα2–3Galβ1–3(NeuAα2–6)GalNAcα1-; 6, GlcNAc-GalNAcα1-; 7, NeuAcα2–6(GlcNAcβ1–3)GalNAcα1-; 8, Galβ1–3(GlcNAcβ1–6) GalNAcα1-; 9, NeuAcα2–3Galβ1–3(GlcNAcβ1–6)GalNAcα1-; 10, Galβ1–3(Galβ1–4GlcNAcβ1–6)GalNAcα1-; 11, NeuAcα2–3Galβ1–3 (Galβ1–4GlcNAcβ1–6)GalNAcα1-. Sequence assumed based on identified sequences on lubricin (38).
b Assignment based on MS/MS using CID, ETD, or both types of fragmentation.
c Glycopeptide MS/MS spectra identified by means of manual annotation or both manual and software-assisted annotation.