Phorbol esters stimulate the phosphorylation of receptors for insulin and somatomedin C.
AUTOR(ES)
Jacobs, S
RESUMO
The effect of phorbol esters on the extent of phosphorylation of receptors for insulin and somatomedin C (insulin-like growth factor I) was studied in intact IM-9 cells that were labeled by incubation with H332PO4. The tumor-promoting phorbol esters phorbol tetradecanoate acetate (TPA) and phorbol dibutyrate, but not the inactive 4 alpha-phorbol, enhanced phosphorylation of the beta subunit of both receptors approximately 4-fold; 70 nM TPA maximally stimulated phosphorylation of both receptors, whereas concentrations less than or equal to 0.7 nM had no observable effect. Insulin also enhanced the phosphorylation of the beta subunit of the insulin receptor, and its effects appeared to be additive to those of TPA. Peptide maps indicated that at least some of the residues phosphorylated by these two agents are distinct. These results suggest a possible role of protein kinase C in regulating insulin and somatomedin C receptors.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=394265Documentos Relacionados
- Phorbol esters stimulate the phosphorylation of c-Jun but not v-Jun: regulation by the N-terminal delta domain.
- Phorbol esters modulate insulin receptor phosphorylation and insulin action in cultured hepatoma cells.
- Monensin blocks the maturation of receptors for insulin and somatomedin C: Identification of receptor precursors
- Phorbol esters, phospholipase C, and growth factors rapidly stimulate the phosphorylation of a Mr 80,000 protein in intact quiescent 3T3 cells.
- Chemical synthesis of a gene for somatomedin C.