Phosphorylation at a tyrosine residue of lipomodulin in mitogen-stimulated murine thymocytes.
AUTOR(ES)
Hirata, F
RESUMO
When murine thymocytes were stimulated by mitogens such as concanavalin A, the Ca2+ ionophore A23187, or 4 beta-phorbol 12-myristate 13-acetate, there was a marked increase of 32P incorporation into immunoprecipitable lipomodulin, a phospholipase inhibitory protein. These compounds enhanced 45Ca2+ influx into thymocytes, which, in turn, increased protein phosphorylation, probably by Ca2+- and phospholipid-dependent protein kinase (protein kinase C). Cyclic 8-bromo-AMP, an inhibitor of lymphocyte mitogenesis, blocked the mitogen-stimulated phosphorylation of lipomodulin, although it stimulated the protein phosphorylation via cyclic AMP-dependent kinase (protein kinase A). On electrophoresis, the hydrolysates of 32P-labeled lipomodulin showed a single radioactive spot, which comigrated with authentic phosphotyrosine. The partially purified middle-sized tumor antigen was able to phosphorylate lipomodulin after being phosphorylated by protein kinase C but not by the catalytic subunit of protein kinase A. Our findings suggest that the activity of a tyrosine-specific kinase, which phosphorylates lipomodulin in vivo as well as in vitro, is stimulated by protein kinase C and inhibited by protein kinase A.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=391561Documentos Relacionados
- Effect of ciprofloxacin on mitogen-stimulated lymphocyte proliferation.
- Mitogen-stimulated phosphorylation of histone H3 is targeted to a small hyperacetylation-sensitive fraction.
- Prostaglandin Suppression of Mitogen-Stimulated Lymphocytes In Vitro: CHANGES WITH MITOGEN DOSE AND PREINCUBATION
- Effects of moxalactam and cefuroxime on mitogen-stimulated human mononuclear leukocytes.
- Dysfunctions of Pokeweed Mitogen-stimulated T and B Lymphocyte Responses Induced by Gammaglobulin Therapy