Table 3. Identification of Ipl1 phosphorylation sites on Sli15 following in vitro phosphorylation.
| Enzyme | Mode a | m/zb observed | m/zb theoretical | Location in Sli15 | Sequencec | Number of phosphates | Phosphorylated residues |
| Lys-C | R | 2870.37 | 2870.50 | 218–242 | (K)VKPPPNSGIARSQRRsNMFVPLPNK | 1 | Ser-233 |
| Lys-C | R | 2887.09 | 2888.28 | 218–242 | (K)VKPPPNSGIARSQRRsNmFVPLPNK | 1 | Ser-233 |
| Lys-C | L | 3771.93 | 3769.96 | 276–310 | (K)sTINSPAIRAVENSDTAGSTKAsSVFDRLSSIPTK | 2 | Ser-276, Ser-298 |
| trypsin | L | 2828.54 | 2829.88 | 285–310 | (R)AVENSDTAGSTKAsSVFDRLsSIPTK | 2 | Ser-298, Ser-305 |
| trypsin | R | 2160.96 | 2160.96 | 319–338 | (R)GNVGHKYsSSSIDLTGSPmK | 1 | Ser-326 |
| Lys-C | R | 2501.10 | 2501.19 | 316–338 | (K)ISRGNVGHKYsSSSIDLTGSPMK | 1 | Ser-326 |
| Lys-C | R | 2517.02 | 2517.18 | 316–338 | (K)ISRGNVGHKYsSSSIDLTGSPmK | 1 | Ser-326 |
| Lys-C | R | 1594.72 | 1594.71 | 378–389 | (K)NSRKssIPRFDK | 2 | Ser-382, Ser-383 |
| Lys-C | R | 2698.98 | 2699.27 | 444–465 | (K)NYYQSPVRGYLRPtKAsISPNK | 2 | Thr-457, Ser-460 |
| trypsin | R | 1611.88 | 1611.83 | 452–465 | (R)GYLRPTKAsISPNK | 1 | Ser-460 |
| Lys-C | L | 2549.92 | 2550.79 | 505–525 | (K)NYRLtNLQLLPPAEAERDDLK | 1 | Thr-509 |
| Lys-C | R | 2549.15 | 2549.28 | 505–525 | (K)NYRLtNLQLLPPAEAERDDLK | 1 | Thr-509 |
| trypsin | R | 1336.65 | 1336.61 | 552–561 | (K)RMsHLEQDLK | 1 | Ser-554 |
| trypsin | R | 1352.64 | 1352.60 | 552–561 | (K)RmsHLEQDLK | 1 | Ser-554 |
| Lys-C | R | 1336.60 | 1336.61 | 552–561 | (K)RMsHLEQDLK | 1 | Ser-554 |
| Lys-C | R | 1352.58 | 1352.60 | 552–561 | (K)RmsHLEQDLK | 1 | Ser-554 |
| Lys-C | R | 1297.54 | 1297.55 | 562–571 | (K)KQtSFSNDYK | 1 | Thr-564 |
| Lys-C | L | 2643.22 | 2642.78 | 572–592 | (K)DIRLKEsLAPFDNHVRDtINK | 2 | Ser-578, Thr-589 |
a
L, linear mode; R, reflector mode.
b
m/z values are average [M+H]+ for linear mode and monoisotopic [M+H]+ for reflector mode.
c
s, phosphoserine; t, phosphothreonine; m, oxidized methionine; (K), (R), residue preceding trypsin/Lys-C cleavage site.