The regulatory phospholipid phosphatidylinositiol-4,5-bisphosphate (PtdIns(4,5)P2) is involved in the regulation of various cellular processes in eukaryotic cells, for instance in the orchestration of vesicle trafficking in polar growth of pollen tubes. In plants, PtdIns(4,5)P2 is synthesized by PI4P 5-kinases. PI4P 5-kinases of different eukaryotic organisms are modulated by phosphorylation. The present dissertation compromises the undirected identification of two evolutionary conserved signaling protein kinases, the mitogen-activated protein kinase MPK6 and the calcium-dependent protein kinase CPK11, that phosphorylate AtPIP5K6 as a substrate. The interplay of AtPIP5K6 and the protein kinases was investigated towards protein-protein interaction, phosphorylation sites and the influence on in vitro activity and in vivo functionality of AtPIP5K6. Summarized, this work contributes to the understanding of plant PI-signaling and establishes new links between evolutionary conserved signaling pathways.