(iv) Calcium-dependent protein phosphorylation in plants

In plant cells, the increase in cytoplasmic calcium [Ca2+]cyt represents a frequent response to various abiotic and biotic stresses. After changes in cytosolic Ca2+ signatures have been sensed, phoshorylation cascades appear to represent general downstream responses in Ca-dependent signal transduction. To elucidate [Ca2+]cyt dependent protein phosphorylation, identify [Ca2+]cyt dependent phosphoproteins, map phosphorylation sites and quantify phosphorylation, we are applying a phosphoproteomics approach, in which Arabidopsis thaliana and Chlamydomonas reinhardtii are taken as model systems.