1y19
From Proteopedia
Structural basis for phosphatidylinositol phosphate kinase type I-gamma binding to talin at focal adhesions
Structural highlights
FunctionPI51C_MOUSE Catalyzes the phosphorylation of phosphatidylinositol 4-phosphate (PtdIns4P) to form phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). PtdIns(4,5)P2 is involved in a variety of cellular processes and is the substrate to form phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3), another second messenger. The majority of PtdIns(4,5)P2 is thought to occur via type I phosphatidylinositol 4-phosphate 5-kinases given the abundance of PtdIns4P. Participates in a variety of cellular processes such as vesicle mediated transport, cell adhesion, cell polarization and cell migration. Together with PIP5K1A is required for phagocytosis, but they regulate different types of actin remodeling at sequential steps. Promotes particle attachment by generating the pool of PtdIns(4,5)P2 that induces controlled actin depolymerization to facilitate Fc-gamma-R clustering. Mediates RAC1-dependent reorganization of actin filaments. Required for synaptic vesicle transport. Controls the plasma membrane pool of PtdIns(4,5)P2 implicated in synaptic vesicle endocytosis and exocytosis. Plays a role in endocytosis mediated by clathrin and AP-2 (adaptor protein complex 2). Required for clathrin-coated pits assembly at the synapse. Participates in cell junction assembly. Modulates adherens junctions formation by facilitating CDH1 trafficking. Required for focal adhesion dynamics. Modulates the targeting of talins (TLN1 and TLN2) to the plasma membrane and their efficient assembly into focal adhesions. Regulates the interaction between talins (TLN1 and TLN2) and beta-integrins. Required for uropodium formation and retraction of the cell rear during directed migration. Has a role in growth factor- stimulated directional cell migration and adhesion. Required for talin assembly into nascent adhesions forming at the leading edge toward the direction of the growth factor. Negative regulator of T-cell activation and adhesion. Negatively regulates integrin alpha-L/beta-2 (LFA-1) polarization and adhesion induced by T-cell receptor. Together with PIP5K1A have a role during embryogenesis and together with PIP5K1B may have a role immediately after birth.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] 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 PubMedThe cytoskeletal protein talin binds to a short C-terminal sequence in phosphatidylinositol phosphate kinase type Igamma (PIPKIgamma), activating the enzyme and promoting the local production of phosphatidylinositol 4,5 bisphosphate, which regulates focal adhesion dynamics as well as clathrin-mediated endocytosis in neuronal cells. Here we show by crystallographic, NMR, and calorimetric analysis that the phosphotyrosine binding (PTB)-like domain of talin engages the PIPKIgamma C terminus in a mode very similar to that of integrin binding. However, PIPKIgamma binds in the canonical PTB-peptide mode with an SPLH motif replacing the classic NPXY motif. The tighter packing of the SPLH motif against the hydrophobic core of talin may explain the stronger binding of PIPKIgamma. Two tyrosine residues flanking the SPLH motif (Tyr-644 and Tyr-649) have been implicated in the regulation of talin binding. We show that phosphorylation at Tyr-644, a Src phosphorylation site in vivo, has little effect on the binding mode or strength, which is consistent with modeling studies in which the phosphotyrosine makes surface-exposed salt bridges, and we suggest that its strong activating effect arises from the release of autoinhibitory restraints in the full-length PIPKIgamma. Modeling studies suggest that phosphorylation of Tyr-649 will likewise have little effect on talin binding, whereas phosphorylation of the SPLH serine is predicted to be strongly disruptive. Our data are consistent with the proposal that Src activity promotes a switch from integrin binding to PIPKIgamma binding that regulates focal adhesion turnover. Structural basis for phosphatidylinositol phosphate kinase type Igamma binding to talin at focal adhesions.,de Pereda JM, Wegener KL, Santelli E, Bate N, Ginsberg MH, Critchley DR, Campbell ID, Liddington RC J Biol Chem. 2005 Mar 4;280(9):8381-6. Epub 2004 Dec 28. PMID:15623515[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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