Table II.

Identification of Arabidopsis S6 carboxy-terminal phosphorylation sites by MADLI-TOF MS analysis

ID Method abbreviations: M, MALDI-TOF; asterisk indicates phosphorylated residue; single underscore indicates candidate phosphorylation sites within peptide.

S6 FormEntry MassTheoretical MassNo. Phosphates PredictedCarboxy-Terminal Peptide SequencePredicted Phosphorylation Status of Carboxy-Terminal Residues from K236 (No. of Phosphates)
m/zm/z
S6547.233546.3470KRSRS6A and S6B: KRSR (0)
S6a528.354528.3471KRS*RS6A and S6B: KRS*R (1)
S6b528.943528.3471KRS*R
1309.721309.7432KRSRLSSAAKRSVTAS6A :KRS*RLSSAAKRSVTA (2)
528.350528.3471KRS*R
1374.521374.8172RSRLSSAPAKPVAAS6B: KRS*RLSSAPAKPVAA (2)
S6c527.470528.3471KRS*R
1066.3401066.6102LSSAAKRSVTAS6A : KRS*RLSSAAKRSVTA (3)
527.439528.3471KRS*R
1200.1301200.7163SRLSSAPAKPVAAS6B: KRS*RLS*S*APAKPVAA (3)
S6d528.144528.3471KRS*R
1048.1901066.6103LSSAAKRSVTA
1429.9201429.8454RSRLSSAAKRSVTAS6A: KRS*RLSSAAKRSVTA (4)
S6e546.423546.3470KRSR
1067.5801066.6102LSSAAKRSVTAS6A: KRSRLSSAAKRSVTA (2)
S6f546.359546.3470KRSR
1048.9301048.6103LSSAAKRSVTAS6A: KRSRLSSAAKRSVTA (3)
S6g546.384546.3470KRSR
1031.5201030.6104LSSAAKRSVTAS6A: KRSRLS*S*AAKRS*VT*A (4)