Table 2.
Identification of tyrosine-phosphorylated tryptic peptides from in vivo-activated MuSK
| Mass | Sequence | No. of P atoms | Phosphorylated residue |
|---|---|---|---|
| 1,215.8 | NIYSADYYK | 1 | Activation loop Y828, Y832, Y833 (Y750, Y754, Y755) |
| 1,295.4 | NIYSADYYK | 2 | |
| 2,310 | NIYSADYYKANENDAIPIR | 1 | |
| 2,390 | NIYSADYYKANENDAIPIR | 2 | |
| 1,235 | LHPNPMYQR | 1 | Juxtamembrane Y631 (Y553 in rat) |
| 1,251 | LHPNPMYQR | 1 | With oxidized M |
| 3,187 | TTETPTLATLPSELLLDRLHPNPMYQR | 1 | |
| 3,203 | TTETPTLATLPSELLLDRLHPNPMYQR | 1 | With oxidized M |
| 986.4 | NNIEYVR | 1 | Beginning of kinase domain Y654 (Y576 in rat) |
The peptide mixtures were analyzed by nanoelectrospray tandem mass spectrometry. Phosphorylated peptides were detected by parent ion scans in the negative ion mode.