Table 1.
Summary of O-glycopeptides identified in HepG2-SC cells and in vitro GalNAc-T enzyme analysis
| Protein name | Sequence† | T1‡ | T2 | T4 | T11 | Sites in T2+§ | Sites in T2− | |
| 16 | AFP | 122 HNCFLAHKKPTPASIPLFQV 141 | −¶ | 1* | − | − | 1 | 0 |
| AHSG | 337 RKTRTVVQPSVGAAAGPVVP 356 | − | 1* | NA | NA | 1 | 0 | |
| APP | 361 PVKLPTTAASTPDAVDK 377 | − | 1 | 1 | − | 1 | 0 | |
| APOC2 | 36 FLTQVKESLSSYWESAKTAA 55 | − | − | − | − | 1 | 0 | |
| APOC3 | 81 FSEFWDLDPEVRPTSAVAA 99 | − | 1* | − | − | 1 | 0 | |
| CRLF1 | 324 AGIWSEWSHPTAASTPRSER 343 | 2–3 | 1–2 | − | − | 1 | 0 | |
| DKK1 | 50 GGAAGHPGSAVSAAPGILYP 69 | 1 | 1 | 1 | 1 | 1 | 0 | |
| IGFBP6 | 117 PKESKPQAGTARPQDVNRRD 136 | 1 | 1 | − | − | 1 | 0 | |
| ITIH2 | 591 QLLAERSLAPTAAAKRRITR 610 | − | 1* | − | − | 1 | 0 | |
| LRP1 I | 3723 GDGTDEEDCEPPTAHTTHCK 3742 | − | − | − | − | 1 | 0 | |
| MATN3 | 43 GPGGSPGRRPSPAAPDGAPA 62 | − | 1* | − | − | 2 | 0 | |
| NPTXR | 72 PALPGAPAASAHPLPPGPLF 91 | − | 1* | − | − | 2 | 0 | |
| OS9 | 521 VVPKKPPPSPQPTEEDPEHR 540 | − | 1–2* | − | − | 1 | 0 | |
| RELN | 174 AQQLCEQGAPTDVTVHPHLA 193 | 1 | 1 | 1 | 1 | 1 | 0 | |
| ROBO1 | 650 DPVKTQDVLPTSQGVDHKQV 669 | − | 1* | − | − | 1 | 0 | |
| STC2 | 241 EAGHHLPEPSSRETGRGAKG 260 | − | − | − | − | 1 | 0 | |
| 10 | APOE | 301 VQAAVGTSAAPVPSDNH 317 | − | 1–2 | 1–2 | − | 2 | 2 |
| DLK1 | 251 SPQQVTRLPSGYGLAYRLTP 270 | 1 | − | NA | 1 | 1 | 1 | |
| GPC6 | 365 RPYNPEERPTTAAGTSLDRL 384 | 1 | 1 | NA | − | 1 | 1 | |
| LRP1 II | 3527 PKEECDERTCEPYQFRCKNN 3546 | − | − | − | − | 1 | 1 | |
| NID1 | 304 GLEDVGTTPFSYKALRRGGA 323 | 1 | 1 | NA | − | 2 | 2 | |
| NUCB1 | 32 GAPNKEETPATESPDTGLYY 51 | 1 | − | 1 | − | 1 | 1 | |
| PLTP | 476 RPADVRASTAPTPSTAAV 493 | 2–3 | 1–2 | NA | NA | 3 | 3 | |
| SDC2 | 91 LNIQNKIPAQTKSPEETDKE 110 | 1 | − | NA | − | 1 | 1 | |
| SDC4 | 90 PERAGSGSQVPTEPKKLEEN 109 | − | − | − | − | 1 | 1 | |
| ST6GalI | 66 SSTQDPHRGRQTLGSLRGLA 85 | 1–3 | − | 1 | − | 3 | 3 | |
| 5 | APOA2 | 45 GKDLMEKVKSPELQAEAKSY 64 | − | − | − | − | 0 | 1 |
| APOF | 262 DQKDANISQPETTKEGLRAI 281 | 1 | 1 | − | − | 0 | 1 | |
| CX3CL1 | 188 VPPVSTAATWQSSAPHQPGP 207 | 1–2 | 1–2 | 1–2 | − | 0 | 4 | |
| IGFBP1 | 159 DGSKALHVTNIKKWKEPCRI 178 | − | − | − | − | 0 | 1 | |
| PRAP1 | 64 PVQKPKLLTTEEKPRGQGRG 83 | − | − | − | − | 0 | 2 |
NA, not analyzed.
*T2-specific sites.
†Sequence of synthetic peptide designed to cover identified O-glycosylation site(s) (underlined).
‡In vitro glycosylation of synthetic peptides using GalNAc-T1, -T2, -T4, and -T11.
§Number of sites identified in glycopeptides from HepG2 SC (T2+) or HepG2 SC/GALNT2−/− (T2−). 0 (glycopeptide not identified), 1, 2, or 3 [1, 2, or 3 site(s) identified].
¶Number of GalNAc residues added to the peptide substrate. (-) no GalNAc added.