May couple lipid signals to the activation-loop phosphorylation of several protein kinases of the so-called AGC kinase family. Interacts via its pleckstrin homology domain with phosphatidic acid, PtdIns3P and PtdIns(3,4)P2 and to a lesser extent with PtdIns(4,5)P2 and PtdIns4P. May play a general role in signaling processes controlling the pathogen/stress response, polar auxin transport and development. Transphosphorylates the AGC protein kinases OXI1/AGC2-1, PK1/S6K1, PK19/S6K2 and PID resulting in their activation. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by phosphatidic acid (PA) and in response to the fungal elicitor xylanase. Interacts with AGC1-5 and AGC1-7 (PubMed:16973627). Interacts with the C-terminal PIF domain of the protein kinases D6PK/AGC1-1, OXI1/AGC2-1 and PID (PubMed:14749726, PubMed:16601102). Membrane-associated after cell stimulation. A number of isoforms are produced. According to EST sequences. Ubiquitous. The PH domain is responsible for the interaction with the 3-phosphoinositides. The activation loop within the kinase domain is the target of phosphorylation. The PIF-binding region in the kinase domain of PDK1 acts as a docking site, enabling it to interact with and enhance the phosphorylation of substrates containing the PIF motif. The PIF-pocket is a small lobe in the catalytic domain required by the enzyme for the binding to the hydrophobic motif of its substrates. It is an allosteric regulatory site that can accommodate small compounds acting as allosteric inhibitors. Phosphorylation on Thr-211 in the activation loop is required for full activity. PDK1 itself can autophosphorylate Thr-211, leading to its own activation. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. PDPK1 subfamily. Truncated N-terminus.