Lo Surdo, P;
Lo Surdo, P;
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Structural and biochemical evaluation of the interaction of the phosphatidylinositol 3-kinase p85alpha Src homology 2 domains with phosphoinositides and inositol polyphosphates.
Journal of Biological Chemistry
15678 - 15685.
Src homology 2 (SH2) domains exist in many intracellular proteins and have well characterized roles in signal transduction. SH2 domains bind to phosphotyrosine (Tyr(P))-containing proteins. Although tyrosine phosphorylation is essential for protein-SH2 domain interactions, the binding specificity also derives from sequences C-terminal to the Tyr(P) residue. The high affinity and specificity of this interaction is critical for precluding aberrant cross-talk between signaling pathways. The p85alpha subunit of phosphoinositide 3-kinase (PI 3-kinase) contains two SH2 domains, and it has been proposed that in competition with Tyr(P) binding they may also mediate membrane attachment via interactions with phosphoinositide products of PI 3- kinase. We used nuclear magnetic resonance spectroscopy and biosensor experiments to investigate interactions between the p85alpha SH2 domains and phosphoinositides or inositol polyphosphates. We reported previously a similar approach when demonstrating that some pleckstrin homology domains show binding specificity for distinct phosphoinositides (Salim, K., Bottomley, M. J., Querfurth, E., Zvelebil, M. J., Gout, I., Scaife, R., Margolis, R. L., Gigg, R., Smith, C. I., Driscoll, P. C., Waterfield, M. D., and Panayotou, G. (1996) EMBO J. 15, 6241-6250). However, neither SH2 domain exhibited binding specificity for phosphoinositides in phospholipid bilayers. We show that the p85alpha SH2 domain Tyr(P) binding pockets indiscriminately accommodate phosphoinositides and inositol polyphosphates. Binding of the SH2 domains to Tyr(P) peptides was only poorly competed for by phosphoinositides or inositol polyphosphates. We conclude that these ligands do not bind p85alpha SH2 domains with high affinity or specificity. Moreover, we observed that although wortmannin blocks PI 3-kinase activity in vivo, it does not affect the ability of tyrosine-phosphorylated proteins to bind to p85alpha. Consequently phosphoinositide products of PI 3-kinase are unlikely to regulate signaling through p85alpha SH2 domains
|Title:||Structural and biochemical evaluation of the interaction of the phosphatidylinositol 3-kinase p85alpha Src homology 2 domains with phosphoinositides and inositol polyphosphates|
|Open access status:||An open access publication|
|Additional information:||UI - 99269107 LA - Eng RN - EC 220.127.116.11 (1-Phosphatidylinositol 3-Kinase) RN - 0 (Androstadienes) RN - 0 (Inositol Phosphates) RN - 0 (Ligands) RN - 0 (Phosphatidylinositols) RN - 19545-26-7 (wortmannin) RN - 21820-51-9 (Phosphotyrosine) PT - JOURNAL ARTICLE DA - 19990629 IS - 0021-9258 SB - M SB - X CY - UNITED STATES JC - HIV AA - Author EM - 199909|
|Keywords:||Phosphatidylinositols, homology, phosphoinositide, polyphosphates, 1-Phosphatidylinositol 3-Kinase, Inositol Phosphates, ligands, Phosphotyrosine, United States, Hiv, 1 Phosphatidylinositol 3 Kinase, 3T3 Cells, Androstadienes, Animal, Binding Sites, Biochemistry, chemistry, genetics, Liposomes, Mice, Models, Molecular, Molecular Biology, Nuclear Magnetic Resonance, peptides, pharmacology, phosphoinositide 3-kinase, Phosphorylation, PI 3-kinase, Proteins, Signal Transduction, spectroscopy, src Homology Domains, Support, Non-U.S.Gov't, Tyrosine, wortmannin|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Life Sciences > Biosciences (Division of)|
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