Table 1.

Identification of Six in Vivo Phosphorylation Sites (S-838, S-858, T-872, T-880, T-982, and S-1168) of Immunoprecipitated BRI1-Flag by Ion Trap or QTOF LC/MS/MS

PeptideaCalculated MassbMeasured MasscCharge StateScoreIonsd
K.EAELEM*YAEGHGNpSGDR.T1960.91960.222.16e14/32
K.EAELEM*YAEGHGNpSGDR.T1960.7269f16/32
K.EAELEM*YAEGHGNpSGDR.T1960.921.75e14/32
K.EALpSINLAAFEKPLR.K1751.91752.8289f16/28
K.LpTFADLIQApTNGFHNDSLIGSGGFGDVYK.A3218.33219.5352f15/56
K.AGVKLNWSpTR.R1211.31211.121.79e7/18
K.EIQAGSGIDSQpSTIR.S1641.61640.922.02e13/28
  • a The amino acid residues appearing before and after the periods correspond to the residues proceeding and following the peptide in the protein sequence. Met sulfoxide is denoted as M*; phosphoseryl and phosphothreonyl residues are denoted as pS and pT, respectively.

  • b Average peptide mass.

  • c Deconvoluted mass determined from the observed m/z at the reported charge state.

  • d The total number of b and y ions (identified/theoretical).

  • e SEQUEST cross-correlation score (Xcorr) of the peptide is based on the fit of the ion trap MS/MS data to the theoretical distribution of ions produced for the peptide.

  • f Mascot score for QTOF analysis.