pp60src-dependent protein phosphorylation in membranes from Rous sarcoma virus-transformed chicken embryo fibroblasts
| Autor: | Dehazya P, G.S. Martin |
|---|---|
| Rok vydání: | 1985 |
| Předmět: |
Phosphopeptides
animal structures Retroviridae Proteins Chick Embryo MAP2K7 Oncogene Protein pp60(v-src) Virology Animals Protein phosphorylation Trypsin Kinase activity Phosphorylation Protein kinase A MAPK14 Rous sarcoma virus biology Cell Membrane Fibroblasts Protein-Tyrosine Kinases biology.organism_classification Molecular biology Peptide Fragments Kinetics Cell Transformation Neoplastic Avian Sarcoma Viruses Mutation Protein Kinases Proto-oncogene tyrosine-protein kinase Src |
| Zdroj: | Virology. 143(2) |
| ISSN: | 0042-6822 |
| Popis: | The Rous sarcoma virus (RSV)-transforming protein, pp60 src , is a plasma membrane-associated tyrosine-specific protein kinase. A 36,000-Da cellular polypeptide (p36) which is phosphorylated at tyrosine in RSV-transformed chicken embryo fibroblasts (RSV-CEF) is also plasma membrane associated. To determine if p36 is directly phosphorylated by pp60 src , and to examine the effects of mutations within src on pp60 src phosphorylation and kinase activity in situ in the plasma membrane, src -dependent protein phosphorylation in membranes isolated from RSV-CEF has been characterized. These membrane preparations contained high ATPase and phosphoprotein phosphatase activities; but when sufficient concentrations of [γ- 32 P]ATP were used, the phosphorylation of pp60 src and the phosphorylation of p36 were linear for 1 min or more, and the initial rates of phosphorylation could therefore be determined. In membranes from RSV-CEF pp60 src and p36 became phosphorylated predominantly at tyrosine, while in membranes from uninfected cells p36 was phosphorylated at low levels at serine. When membranes from RSV-CEF were preincubated with tumor-bearing rabbit (TBR) serum, the IgG became phosphorylated while the phosphorylation of p36 was inhibited, suggesting that p36 is directly phosphorylated by pp60 src . Phosphorylation of pp60 src , p36, and TBR-IgG was dependent on growth temperature in membranes from cells infected by a temperature-sensitive mutant, ts NY68, although some dependence on growth temperature was observed even with membranes from wild-type RSV-infected cells. However, at the nonpermissive temperature, ts NY68 pp60 src retained 20–40% of its kinase activity, providing supporting for the proposal (B. M. Sefton, T. Hunter, and K. Beemon (1980, J. Virol , 33 , 220–229) that transformation may result from a small quantitative change in pp60 src activity. The phosphorylation of pp60 src and its kinase activity were not coordinately affected by growth temperature or mutations within src , indicating that different factors affect the phosphoacceptor capacity and kinase activity of the protein. |
| Databáze: | OpenAIRE |
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