The human IgA Fc receptor (FcalphaR, CD89) triggers several important physiological functions, including phagocytosis, NADPH oxidase activation and antigen presentation. Efforts are underway to delineate FcalphaR signal-transduction pathways that control these functions. In a previous study, we demonstrated that cross-linking of FcalphaR increased its partitioning into membrane glycolipid rafts...

Insulin receptor tyrosine kinase activation, induced by insulin-stimulated autophosphorylation, was measured using a synthetic peptide containing residues 1142-1153 of the insulin receptor and shown to be reversed by both particulate and soluble phosphotyrosyl protein phosphatases from rat liver. Deactivation of the tyrosine kinase was highly sensitive to phosphatase action and was correlated b...

Tec family kinases, which include tyrosine kinase expressed in hepatocellular carcinoma (TEC), Bruton's tyrosine kinase (BTK), interleukin (IL)-2-inducible T-cell kinase (ITK), tyrosine-protein kinase (TXK), and bone marrow tyrosine kinase on chromosome X (BMX), are the second largest group of non-receptor tyrosine kinases and have a highly conserved carboxyl-terminal kinase domain. BMX was ide...

The ATPase associated with different cellular activities family member p97, associated p47, and the t-SNARE syntaxin 5 are necessary for the cell-free reconstitution of transitional endoplasmic reticulum (tER) from starting low-density microsomes. Here, we report that membrane-associated tyrosine kinase and protein-tyrosine phosphatase (PTPase) activities regulate tER assembly by stabilizing (P...

The shear-induced intracellular signal transduction pathway in vascular endothelial cells involves tyrosine phosphorylation and activation of mitogen-activated protein (MAP) kinase, which may be responsible for the sustained release of nitric oxide. MAP kinase is known to be activated by reactive oxygen species (ROS), such as H2O2, in several cell types. ROS production in ligand-stimulated nonp...

Tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) by the insulin receptor permits this docking protein to interact with signaling proteins that promote insulin action. Serine phosphorylation uncouples IRS-1 from the insulin receptor, thereby inhibiting its tyrosine phosphorylation and insulin signaling. For this reason, there is great interest in identifying serine/threonine kina...

Increasing evidence supports the hypothesis that tannic acid, a plant polyphenol, exerts anticarcinogenic activity in chemically induced cancers. In the present study, tannic acid was found to strongly inhibit tyrosine kinase activity of epidermal growth factor receptor (EGFr) in vitro (IC50 = 323 nM). In contrast, the inhibition by tannic acid of p60(c-src) tyrosine kinase (IC50 = 14 microM) a...

Bruton's tyrosine kinase (Btk) plays critical roles in B cell development and activation. Mutations of Btk cause X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency in mice. An Src homology domain 2-kinase linker region exists in all Src, Abl, ZAP70/Syk and Btk/Tec non-receptor tyrosine kinase families. Missense mutations in the Btk linker region can cause XLA, supporting ...

Abstract Tyrosine kinase 2 (TYK2) is a member of the JAK family nonreceptor tyrosine kinase, together with JAK1, JAK2, and JAK3. JAKs are important signaling mediators many proinflammatory cytokines represent compelling pharmacological targets for autoimmune inflammatory diseases. Pan-acting small-molecule inhibitors were approved treatment rheumatoid arthritis ulcerative colitis. However, thei...

Abscisic acid (ABA) induces a rapid and transient mitogen-activated protein (MAP) kinase activation in barley aleurone protoplasts. MAP kinase activity, measured as myelin basic protein phosphorylation by MAP kinase immunoprecipitates, increased after 1 min, peaked after 3 min, and decreased to basal levels after ~5 min of ABA treatment in vivo. Antibodies recognizing phosphorylated tyrosine re...