Pleckstrin homology (PH) domain-mediated protein recruitment to cellular membranes is of paramoun... more Pleckstrin homology (PH) domain-mediated protein recruitment to cellular membranes is of paramount importance for signal transduction. The recruitment of many PH domains is controlled through production and turnover of their membrane ligand, phosphatidylinositol 3,4,5-trisphosphate (PIP3). We show that phosphorylation of the second messenger inositol 1,4,5-trisphosphate (IP3) into inositol 1,3,4,5-tetrakisphosphate (IP4) establishes another mode of PH domain regulation through a soluble ligand. At physiological concentrations, IP4 promoted PH domain binding to PIP3. In primary mouse CD4+CD8+ thymocytes, this was required for full activation of the protein tyrosine kinase Itk after T cell receptor engagement. Our data suggest that IP4 establishes a feedback loop of phospholipase C-gamma1 activation through Itk that is essential for T cell development.
The cleavage of mandelonitrile catalysed by hydroxynitrile lyases (HNL) from Prunus amygdalus (Pa... more The cleavage of mandelonitrile catalysed by hydroxynitrile lyases (HNL) from Prunus amygdalus (PaHNL) and Manihot esculenta (MeHNL) proceeded more rapidly in monophasic aqueous media containing 1-propyl-3-methylimidazolium tetrafluoroborate [C4MIm][BF4] than in media containing acetonitrile or THF. Both HNLs were much more thermostable in [C4MIm][BF4] than in acetonitrile or THF. The addition of each of the four ionic liquids 1-butyl-, 1-pentyl- and 1-hexyl-3-methylimidazolium tetrafluoroborates at 2-6% (v/v in the aqueous phase) increased both the enzyme activity and the product e.e. in the PaHNL-catalysed transcyanation in an aqueous/DIPE biphasic system. However, MeHNL was inactivated by the ionic liquids, as indicated by the decreased reaction rate, substrate conversion and product e.e.
... Correspondence: Min-Hua Zong, Department of Biotechnology, South ... Structure 1994; 2: 2933... more ... Correspondence: Min-Hua Zong, Department of Biotechnology, South ... Structure 1994; 2: 293308. Zhao H, Luo RG, Malhotra SV. Kinetic study on the enzymatic resolution of homophenylaianine ester using ionic liquids. Biotechnol Prog 2003; 19: 10168. Zhao H, Malhotra ...
During T cell signaling, Itk selectively phosphorylates a tyrosine within its own SH3 domain and ... more During T cell signaling, Itk selectively phosphorylates a tyrosine within its own SH3 domain and a tyrosine within PLCγ1. We find that the remote SH2 domain in each of these substrates is required to achieve efficient tyrosine phosphorylation by Itk and extend this observation to two ...
Pleckstrin homology (PH) domain-mediated protein recruitment to cellular membranes is of paramoun... more Pleckstrin homology (PH) domain-mediated protein recruitment to cellular membranes is of paramount importance for signal transduction. The recruitment of many PH domains is controlled through production and turnover of their membrane ligand, phosphatidylinositol 3,4,5-trisphosphate (PIP3). We show that phosphorylation of the second messenger inositol 1,4,5-trisphosphate (IP3) into inositol 1,3,4,5-tetrakisphosphate (IP4) establishes another mode of PH domain regulation through a soluble ligand. At physiological concentrations, IP4 promoted PH domain binding to PIP3. In primary mouse CD4+CD8+ thymocytes, this was required for full activation of the protein tyrosine kinase Itk after T cell receptor engagement. Our data suggest that IP4 establishes a feedback loop of phospholipase C-gamma1 activation through Itk that is essential for T cell development.
The cleavage of mandelonitrile catalysed by hydroxynitrile lyases (HNL) from Prunus amygdalus (Pa... more The cleavage of mandelonitrile catalysed by hydroxynitrile lyases (HNL) from Prunus amygdalus (PaHNL) and Manihot esculenta (MeHNL) proceeded more rapidly in monophasic aqueous media containing 1-propyl-3-methylimidazolium tetrafluoroborate [C4MIm][BF4] than in media containing acetonitrile or THF. Both HNLs were much more thermostable in [C4MIm][BF4] than in acetonitrile or THF. The addition of each of the four ionic liquids 1-butyl-, 1-pentyl- and 1-hexyl-3-methylimidazolium tetrafluoroborates at 2-6% (v/v in the aqueous phase) increased both the enzyme activity and the product e.e. in the PaHNL-catalysed transcyanation in an aqueous/DIPE biphasic system. However, MeHNL was inactivated by the ionic liquids, as indicated by the decreased reaction rate, substrate conversion and product e.e.
... Correspondence: Min-Hua Zong, Department of Biotechnology, South ... Structure 1994; 2: 2933... more ... Correspondence: Min-Hua Zong, Department of Biotechnology, South ... Structure 1994; 2: 293308. Zhao H, Luo RG, Malhotra SV. Kinetic study on the enzymatic resolution of homophenylaianine ester using ionic liquids. Biotechnol Prog 2003; 19: 10168. Zhao H, Malhotra ...
During T cell signaling, Itk selectively phosphorylates a tyrosine within its own SH3 domain and ... more During T cell signaling, Itk selectively phosphorylates a tyrosine within its own SH3 domain and a tyrosine within PLCγ1. We find that the remote SH2 domain in each of these substrates is required to achieve efficient tyrosine phosphorylation by Itk and extend this observation to two ...
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