TABLE 1.
Phosphopeptides identified by liquid chromatography tandem mass spectrometrya
| Peptide sequence | Phospho-S |
m/z |
|
|---|---|---|---|
| Calc | Expt | ||
| p38 MAPKα + HSF1 | |||
| K.EEPPS303PPQS307PR.V | S303/307 | 1,299.5496 | 1,299.5487 |
| R.VKEEPPS303PPQS307PR.V | S303/307 | 1,526.7130 | 1,526.7121 |
| R.VEEASPGRPSSVDTLLS326PTALIDSILR.E | S326 | 2,902.4689 | 2,902.4659 |
| p38 MAPKδ + HSF1 | |||
| K.EEPPS303PPQS307PR.V | S303/307 | 1,299.5496 | 1,299.5493 |
| R.VKEEPPS303PPQS307PR.V | S303/307 | 1,526.7130 | 1,526.7121 |
| R.VEEASPGRPSSVDTLLS326PTALIDSILR.E | S326 | 2,902.4689 | 2,902.4683 |
a
Phosphopeptides were identified by liquid chromatography-tandem mass spectrometry after 60 min incubation of recombinant human HSF1 (1.0 μg) with p38 MAPKα or p38 MAPKδ (0.06 mU/μl), followed by SDS-PAGE separation and in-gel tryptic digestion. The phosphorylated residue is indicated by boldfacing in column 1. Calc, calculated; Expt, expected.