1w1d
Crystal Structure of the PDK1 Pleckstrin Homology (PH) domain bound to Inositol (1,3,4,5)-tetrakisphosphate
Structural highlights
FunctionPDPK1_HUMAN Serine/threonine kinase which acts as a master kinase, phosphorylating and activating a subgroup of the AGC family of protein kinases. Its targets include: protein kinase B (PKB/AKT1, PKB/AKT2, PKB/AKT3), p70 ribosomal protein S6 kinase (RPS6KB1), p90 ribosomal protein S6 kinase (RPS6KA1, RPS6KA2 and RPS6KA3), cyclic AMP-dependent protein kinase (PRKACA), protein kinase C (PRKCD and PRKCZ), serum and glucocorticoid-inducible kinase (SGK1, SGK2 and SGK3), p21-activated kinase-1 (PAK1), protein kinase PKN (PKN1 and PKN2). Plays a central role in the transduction of signals from insulin by providing the activating phosphorylation to PKB/AKT1, thus propagating the signal to downstream targets controlling cell proliferation and survival, as well as glucose and amino acid uptake and storage. Negatively regulates the TGF-beta-induced signaling by: modulating the association of SMAD3 and SMAD7 with TGF-beta receptor, phosphorylating SMAD2, SMAD3, SMAD4 and SMAD7, preventing the nuclear translocation of SMAD3 and SMAD4 and the translocation of SMAD7 from the nucleus to the cytoplasm in response to TGF-beta. Activates PPARG transcriptional activity and promotes adipocyte differentiation. Activates the NF-kappa-B pathway via phosphorylation of IKKB. The tyrosine phosphorylated form is crucial for the regulation of focal adhesions by angiotensin II. Controls proliferation, survival, and growth of developing pancreatic cells. Participates in the regulation of Ca(2+) entry and Ca(2+)-activated K(+) channels of mast cells. Essential for the motility of vascular endothelial cells (ECs) and is involved in the regulation of their chemotaxis. Plays a critical role in cardiac homeostasis by serving as a dual effector for cell survival and beta-adrenergic response. Plays an important role during thymocyte development by regulating the expression of key nutrient receptors on the surface of pre-T cells and mediating Notch-induced cell growth and proliferative responses. Provides negative feedback inhibition to toll-like receptor-mediated NF-kappa-B activation in macrophages. Isoform 3 is catalytically inactive.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed3-phosphoinositide-dependent protein kinase-1 (PDK1) phosphorylates and activates many kinases belonging to the AGC subfamily. PDK1 possesses a C-terminal pleckstrin homology (PH) domain that interacts with PtdIns(3,4,5)P3/PtdIns(3,4)P2 and with lower affinity to PtdIns(4,5)P2. We describe the crystal structure of the PDK1 PH domain, in the absence and presence of PtdIns(3,4,5)P3 and Ins(1,3,4,5)P4. The structures reveal a 'budded' PH domain fold, possessing an N-terminal extension forming an integral part of the overall fold, and display an unusually spacious ligand-binding site. Mutagenesis and lipid-binding studies were used to define the contribution of residues involved in phosphoinositide binding. Using a novel quantitative binding assay, we found that Ins(1,3,4,5,6)P5 and InsP6, which are present at micromolar levels in the cytosol, interact with full-length PDK1 with nanomolar affinities. Utilising the isolated PDK1 PH domain, which has reduced affinity for Ins(1,3,4,5,6)P5/InsP6, we perform localisation studies that suggest that these inositol phosphates serve to anchor a portion of cellular PDK1 in the cytosol, where it could activate its substrates such as p70 S6-kinase and p90 ribosomal S6 kinase that do not interact with phosphoinositides. Structural insights into the regulation of PDK1 by phosphoinositides and inositol phosphates.,Komander D, Fairservice A, Deak M, Kular GS, Prescott AR, Peter Downes C, Safrany ST, Alessi DR, van Aalten DM EMBO J. 2004 Oct 13;23(20):3918-28. Epub 2004 Sep 30. PMID:15457207[16] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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