TABLE 3.
Phosphopeptides identified from in situ autophosphorylated recombinant CPK28
Data shown are from representative peptide identifications; all product ion spectra were inspected manually to ensure correct phosphosite identification.
| Sitea | Mr (experimental) | Mr (calculated) | E-value | Peptide | Fragmentation | Ref. |
|---|---|---|---|---|---|---|
| Ser-6 | 988.4201 | 988.4202 | 0.0041 | M.GVCFpSAIR.V | HCD | |
| Ser-24 | 1207.5859 | 1207.5849 | 4.2e-07 | K.pSKAAPTPIDTK.A | HCD | 16 |
| Thr-33 | 1379.6712 | 1379.6697 | 0.00032 | K.AAPTPIDpTKASTK.R | HCD | 16 |
| Ser-36 | 1379.6718 | 1379.6697 | 0.00095 | K.AAPTPIDTKApSTK.R | HCD | 16 |
| Thr-33/Thr-37 | 1615.7376 | 1615.7372 | 0.00043 | K.AAPTPIDpTKASpTK.R | ETD | |
| Ser-43 | 898.3620 | 898.3620 | 0.0014 | R.TGpSIPCGK.R | HCD | 16 |
| Ser-198 | 1037.4808 | 1037.4794 | 1.0e-05 | K.pSAQLDSPLK.A | HCD | |
| Ser-228 | 1986.9549 | 1986.9492 | 5.1e-10 | R.FHDIVGpSAYYVAPEVLK.R | HCD | 16, 17, 27 |
| Ser-318 | 1502.7392 | 1502.7395 | 6.0e-05 | R.LTAAQALpSHAWR.E | HCD | 16, 17, 27 |
| Thr-329 | 2075.9707 | 2075.9888 | 0.0016 | R.EGGNApTDIPVDISVLNNLR.Q | HCD | |
| Ser-360 | 1682.7788 | 1682.7764 | 9.5e-09 | R.ALApSTLDEAEISDLR.D | HCD | |
| Tyr-463b | 1271.5453 | 1271.5435 | 0.0036 | K.DGpYITPEELR.M | HCD | 16 |
| Ser-478 | 1607.7088 | 1607.7080 | 3.9e-06 | R.GpSIDPLLDEADIDR.D | HCD | - |
| Ser-495 | 1280.5914 | 1280.5914 | 0.00058 | R.DGKIpSLHEFR.R | HCD | 17, 27 |
| Ser-510 | 928.4015 | 928.4015 | 0.0002 | R.TASISpSQR.A | HCD | |
| Ser-510 | 1701.7954 | 1701.7948 | 3.0e-10 | R.TASISpSQRAPSPAGHR.N | ETD | |
| Ser-507/Ser-510 | 1008.3676 | 1008.3678 | 0.039 | R.TApSISpSQR.A | HCD | |
| Ser-507/Ser-510 | 1781.7618 | 1781.7611 | 0.00013 | R.TApSISpSQRAPSPAGHR.N | ETD |
a Sites listed in boldface are new sites identified only in this study.
b Tyr(P)-463 was only identified in samples from protein expressed with the addition of CaCl2 to the expression culture at the time of induction.