Perception of the peptide hormone Systemin

Cell suspension cultures of Solanum peruvianum were subjected to stimulation with 10nM systemin, the inactive systemin analog10nM a17, or injected with equal volume of water. For each treatment, a batch of cells was harvested after 2 minutes, 5 minutes, 15 minutes and 45 minutes. Untreated cells were harvested as controls. All treatments and time points were sampled as three independent replicates using independent sets of cells. Microsomal membranes were isolated from each sample, digested with trypsin, enriched for phosphopeptides and subjected to untargeted data-dependent acquisition by LC-MS/MS. Data analysis was performed jointly for all samples, and intensity values of triplicates were averaged.