We have used two approaches to identify possible substrates of the insulin receptor (IR) tyrosine kinase. First, we used a potent tyrosine phosphatase inhibitor, phenylarsine oxide (PAO), which is reported to be specific for the insulin-induced signal transduction route, to augment tyrosine phosphorylation. Second, we used src homology 2 (SH2) domains fused to glutathione S-transferase as high ...

Binding of GH to GH receptor (GHR) rapidly and transiently activates multiple signal transduction pathways that contribute to the growth-promoting and metabolic effects of GH. While the events that initiate GH signal transduction, such as activation of the Janus tyrosine kinase JAK2, are beginning to be understood, the signaling events that terminate GH signaling, such as dephosphorylation of t...

This work presents a simple, low-cost and reusable label-free method for detecting protein tyrosine kinase activity using a tyrosinase-based amperometric biosensor (tyrosine kinase biosensor). This method is based on the observation that phosphorylation can block the tyrosinase-catalyzed oxidation of tyrosine or tyrosyl residue in peptides. Therefore, the activity of p60c-src protein tyrosine k...

Driver tyrosine kinase mutations are rare in sarcomas, and patterns of tyrosine phosphorylation are poorly understood. To better understand the signaling pathways active in sarcoma, we examined global tyrosine phosphorylation in sarcoma cell lines and human tumor samples. Anti-phosphotyrosine antibodies were used to purify tyrosine phosphorylated peptides, which were then identified by liquid c...

The regulation of tyrosine production in the anthramycin-producing organism Streptomyces refuineus var. thermotolerans has been studied with wild-type and tyrosine auxotrophic organisms. Growth of the auxotroph on minimal medium plus phenylalanine suggested that phenylalanine may increase the supply of tyrosine. In incubation with whole cells, tyrosine levels increased in response to added phen...

We show the presence of the tyrosine kinase JAK2 in human platelets and demonstrate that it undergoes phosphorylation on tyrosine residues on challenge with the G protein receptor stimulus, thrombin, or the tyrosine phosphatase inhibitor, peroxovanadate. Thrombin-induced phosphorylation of JAK2 is inhibited by two structurally distinct inhibitors of tyrosine kinases, staurosporine and the tyrph...

Topica! tyrosine has been proposed as a tanning accelerator because tyrosine is a precursor of melanin. We tested formulations containing O, 1, and 2% L-tyrosine topically on 14 individuals daily for 28 days. Percutaneous absorption using "C tyrosine was 1.23% in 24 hr. No enhanced pigmentation was clinically evident in any of the subjects. In this study, we were unable to demonstrate that topi...

Tyrosine kinase inhibitors are a new class of anticancer drugs, that are capable of directly interacting with the catalytic site of the target enzyme and thereby inhibiting catalysis. Therapeutically useful tyrosine kinase inhibitors are not specific for a single tyrosine kinase, but rather they are selective against a limited number of tyrosine kinases. The success of imatinib-mesylate (Gleeve...

Many investigators of tyrosine oxidation have used systems in vitro such as slices, minces, and, more recently, homogenates of liver. During our search for a suitable preparation other than liver slices for studying the conversion of phenylalanine to tyrosine, an extract of rat liver acetone powder was tested. Although the phenylalanine to tyrosine conversion was not demonstrated, it was found ...

The erythropoietin (Epo) receptor belongs to the cytokine receptor superfamily. Although the cytokine receptors do not possess a tyrosine kinase consensus sequence in the intracellular domain, rapid stimulation of a tyrosine kinase activity occurs after activation by the ligand. We and others have shown that Epo induces the tyrosine phosphorylation of its cognate receptor as well as phosphoryla...