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...

The delta isoform of protein kinase C is phosphorylated on tyrosine in response to antigen activation of the high-affinity receptor for immunoglobulin E. While protein kinase C-delta associates with and phosphorylates this receptor, immunoprecipitation of the receptor revealed that little, if any, tyrosine-phosphorylated protein kinase C-delta is receptor associated. In vitro kinase assays with...

Insulin binding and receptor tyrosine kinase activity were investigated in the insulin-responsive R3230AC mammary adenocarcinoma. Insulin receptors, partially purified by wheat germ agglutinin-agarose Chroma tograph), displayed electrophoretic properties similar to those of normal tissues and demonstrated autophosphorylation of the ft subunit. Tyrosine kinase activity of tumor preparations was ...

von Willebrand factor (vWF ) in the presence of botrocetin induces p72(syk) activation, assessed as its autophosphorylated level and in vitro kinase assays, the transient association of p72(syk) with p60(c-src), and the translocation of p60(c-src) and p54/58(lyn) to cytoskeletal fractions. Jararaca glycoprotein Ib-binding protein (GPIb-BP), which specifically binds to GPIb, abolished these phen...

Mutation of the epidermal growth factor receptor (EGF-R) within the ATP binding subdomain results in a receptor that lacks tyrosine kinase activity and is defective in signal transduction. However, this kinase-negative EGF-R is able to activate MAP kinase (Campos-Gonzalez, R., and Glenny, J. R. (1992) J. Biol. Chem. 267, 14535-14538). This observation suggests that signal initiation by the EGF-...

Recent evidence indicates that tyrosine phosphorylation may play important roles in retinal photoreceptor rod outer segments (ROS). We investigated the tyrosine phosphorylation of endogenous proteins in isolated bovine ROS. Several proteins with apparent molecular masses of 31, 39, 60, 83, 90, 97, 120, 140, and 180 kDa were tyrosine-phosphorylated in ROS incubated with Mg(2+), ATP, and orthovan...