phosphorus-radioisotopes has been researched along with oxophenylarsine* in 2 studies
2 other study(ies) available for phosphorus-radioisotopes and oxophenylarsine
| Article | Year |
|---|---|
Induction of hyperphosphorylation and activation of the p56lck protein tyrosine kinase by phenylarsine oxide, a phosphotyrosine phosphatase inhibitor.
The T cell protein tyrosine kinase p56lck is implicated in thymic development and mitogenic activation of T lymphocytes, and is itself regulated by reversible tyrosine phosphorylation. When phenylarsine oxide (PAO), a membrane-permeable inhibitor of phosphotyrosine phosphatases, was added to Jurkat T leukemia or LSTRA thymoma cells, the phosphate content of p56lck increased rapidly. The sites of increased phosphorylation were mapped to Tyr-192, Tyr-394 and Tyr-505. Hyperphosphorylated p56lck displayed retarded mobility on SDS gels, unaltered or marginally increased cytoskeletal association, and its catalytic activity changed in a biphasic manner; during the first 10-20 min of PAO-treatment the activity increased and then it declined to very low values within 1-2 hr. Our data suggest that p56lck contains both positive and negative regulatory sites which are constantly dephosphorylated at an unexpectedly high rate by cellular phosphotyrosine phosphatases. Topics: Animals; Arsenicals; Cell Line, Transformed; Cytoskeleton; Enzyme Activation; Humans; Lymphocyte Specific Protein Tyrosine Kinase p56(lck); Mice; Peptide Mapping; Phosphorus Radioisotopes; Phosphorylation; Protein Tyrosine Phosphatases; Protein-Tyrosine Kinases; Tumor Cells, Cultured | 1994 |
Insulin-activated tyrosine phosphorylation of a 15-kilodalton protein in intact 3T3-L1 adipocytes.
Insulin stimulates phosphorylation of a tyrosine residue(s) on a 15-kDa protein (p15), and the cytosolic phosphorylated protein (pp15) accumulates only when 3T3-L1 adipocytes are treated with phenylarsine oxide. It has been shown previously that phenylarsine oxide, an agent that complexes vicinal dithiols, interrupts signal transmission from the insulin receptor to the glucose transport system. Several lines of evidence presented here indicate the involvement of pp15 in insulin receptor-initiated signal transduction to the glucose transport system. The reciprocal effects of phenylarsine oxide on the insulin-activated accumulation of pp15 and on insulin-stimulated hexose uptake are reversed by the vicinal dithiol 2,3-dimercaptopropanol but not by the monothiol 2-mercaptoethanol. Thus, a cellular dithiol appears to function in the signal transmission pathway downstream from pp15. Like the insulin-activated autophosphorylation of the receptor's beta subunit (on tyrosine), activation of phosphorylation of p15 is specific, with insulin-like growth factors 1 and 2, epidermal growth factor, and platelet-derived growth factor being inactive. Moreover, both processes exhibit identical insulin concentration dependence. The temporal kinetic relationship of insulin-activated receptor beta-subunit phosphorylation, followed by the phosphorylation of p15 and then increased hexose uptake rate, is consistent with an intermediary signaling role for pp15 in insulin-stimulated glucose uptake. Topics: Adipose Tissue; Animals; Arsenicals; Cells, Cultured; Enzyme Activation; Insulin; Kinetics; Mice; Molecular Weight; Phosphorus Radioisotopes; Phosphorylation; Protein-Tyrosine Kinases; Proteins; Receptor, Insulin | 1987 |