※ PDK1 family introduction

    PDK1 (phosphoinositide-dependent protein kinase 1) belongs to AGC group. Two isoforms have been identified in human genome, known as PDK1 and PDK2. PDK1 now is well understood and regarded as a key regulator in varieties of cellular processes. PDK1 was first purified as an enzyme that could phosphorylate the T-loop of PKBα (Thr308) in the presence of PtdIns(3,4,5)P3. Sequence analysis shows that PDK1 consists of kinase catalytic domain in its N-terminus and a Pleckstrin homology (PH) domain at its C-terminus. PDK1 posses the high catalytic activity regulated by its intrinsic ability that phosphorylates its own T-loop residue. PDK1 is characterized by its major role in regulation of AGC kinase signal transduction. Studies show that PKB PH domain can bind 3-phosphoinositide and induce a large conformational change in PKB and the phosphorylation of PKB by PDK1 can be available. In addition, S6K and SGK are also under the regulation of PDK1 by phosphorylation (1).

Reference
1. Mora, A., Komander, D., van Aalten, D.M. and Alessi, D.R. (2004) PDK1, the master regulator of AGC kinase signal transduction. Semin Cell Dev Biol, 15, 161-170. PMID: 15209375.