Table I

Phosphopeptides from Pho4 grown in phosphate-rich medium

PeakMWdetaPho4bSequencecResidue
13575.780–110 + PAFELVEGMDMDWMMPSHAHHpSPATTATIKPRSer100 (S1)
2d3476.4111–143 + PLLYpSPLIHTQSAVPVTISPNLVATATSTTSANKSer114 (S2)
2d3476.4111–143 + PLLYSPLIHTQSAVPVTIpSPNLVATATSTTSANKSer128 (S3)
33557.7111–143 + 2P**LLYSPLIHTQSAVPVTISPNLVATATSTTSANKNDe
4d1088.8147–157 + PNKSNSpSPYLNKSer152 (S4)
4d1088.8147–157 + PNKSNpSSPYLNKSer151
5936.5202–209 + PRVpSPVTAKSer204 (S5)
6d2615.6210–235 + PTSSSAEGVVVASEpSPVIAPHGSSHSRSer223 (S6)
6d2615.6210–235 + PTSSSAEGVVVASESPVIAPHGSSHSRND
72694.9210–235 + 2P**TSSSAEGVVVASESPVIAPHGSSHSRND
8d1824.74–19 + PTTSEGIHGFVDDLEPKThr4/Thr5f
8d1824.74–19 + PTTpSEGIHGFVDDLEPKSer6
92659.5160–184 + PGKPGPDpSATSLFELPDSVIPTPKPKSer167
101242.3242–252 + PSSGALVDDDKRSer242/Ser243f
111398.1241–252 + PRSpSGALVDDDKRSer243
121554.2240–252 + PRRSpSGALVDDDKRSer242
131634.2240–252 + 2P**RRpSpSGALVDDDKRSer242, Ser243
141526.1*240–252 + P*RRSpSGALVDDDKRSer243
155069.637–79 + P**HDGREDFNEQNDELNSQENHNSSENGNENENEQDSLALDDLDRND
165148.437–79 + 2P**HDGREDFNEQNDELNSQENHNSSENGNENENEQDSLALDDLDRND
  • a Determined molecular weight.

  • b Predicted tryptic peptide plus phosphate from Pho4 (P07270).

  • c All sequences have been verified by tandem mass spectrometry unless where otherwise noted (**). Confirmed phosphorylation sites are shown in bold face as pS (phosphoserine). In cases were the site of phosphorylation is ambiguous, the ambiguous residues are underlined, and the likely sites of phosphorylation are shown in bold face. *, the peptide contains an unknown modification in the first two residues that resulted in a mass shift of minus 28 Da. We did not routinely observe this species.

  • d During LC-MS analysis peaks 2, 4, and 8 eluted from reverse phase chromatography as two peaks, each containing a single site of phosphorylation.

  • e ND, sites not determined.

  • f We were unable to distinguish between these two sites.