Figure S1. Venn diagram of the distribution phosphopeptides to the different treatments. (a) All unique phosphopeptides sequences identified in the different experiments. (b) Unique phosphopeptides that could be quantified at least at three different time points.

Figure S2. NRT2.1 phosphorylation and nitrate uptake (a) Targeted analysis of NRT2.1 phosphorylation under different concentrations of nitrate resupply for 10 min. Normalized ion intensities of the phosphorylated form (red) and non-phosphorylated form (gray) are plotted as average of three biological replicates (b) 15N-Nitrate uptake of seedlings resupplied with different concentrations of nitrate under conditions of high- and low-affinity nitrate uptake.

Figure S3. Venn diagram of the identified phosphopeptides under nitrate and ammonium resupply and the respective non-phosphorylated peptides identified under the same conditions in the same respective samples.

Figure S4. Phosphorylation time course profiles for phosphopeptides identified from glutamine synthase 1 isoforms and total GS enzymes activitiy. (a) Phosphorylation time course for GS1.1 (b) phosphorylation time course for GS1.2, (c) phosphorylation time course for GS1.3 (d) Total activity of glutamine synthase in nitrate and ammonium resupplied seedlings.

Figure S5. Boxplot of the relative standard deviation of all quantified peptides averaged over all 12 replicated experiments.

Figure S6. Overlap of proteins found with change in phosphorylation and with significant changes in transcript levels upon nitrate resupply after nitrogen starvation.

Figure S7. All phosphopeptide spectra as exported from the respective entry in the public database PhosPhAt (

Table S1. List of all phosphopeptides. The first worksheet contains the mass spectrometric evidence for each phosphopeptide by listing mass to charge ratio, MASCOT identification score, PTM score. The second worksheet contains the normalized ion intensities used for quantitation as well as additional information about sequence motifs, or putative MAP-kinase substrates.

Appendix S1. Glutamine synthase activity; targeted analysis of protein phosphorylation by single reaction monitoring; nitrate uptake assays.

As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer-reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors.

TPJ_4848_sm_AppendixS1.rtf42KSupporting info item
TPJ_4848_sm_FigS1.jpg2221KSupporting info item
TPJ_4848_sm_FigS2.JPG1419KSupporting info item
TPJ_4848_sm_FigS3.JPG1113KSupporting info item
TPJ_4848_sm_FigS4.JPG2757KSupporting info item
TPJ_4848_sm_FigS5.JPG441KSupporting info item
TPJ_4848_sm_FigS6.pdf103KSupporting info item
TPJ_4848_sm_FigS7.pdf10992KSupporting info item
TPJ_4848_sm_Legends.rtf41KSupporting info item
TPJ_4848_sm_TableS1a.txt538KSupporting info item
TPJ_4848_sm_TableS1b.txt1406KSupporting info item

Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.