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Correlation between phosphorylation of a 34,000-molecular-weight protein, pp60src-associated kinase activity, and
Abstract:
The phosphorylation of a 34,000-molecular-weight (34K) cell protein, purported to be a substrate of the avian retrovirus pp60src-associated protein kinase activity, was compared in three types of Rous sarcoma virus-infected vole cells: fully transformed cells, partial revertants which are morphologically normal in appearance but retain their tumorigenic potential, and full revertants which are similar to normal vole cells in all parameters including a lack of tumorigenicity. Although similar amounts of 34K protein are present in all three cell types, phosphorylation of the 34K protein was significantly reduced in the full revertant cell type. The reduced phosphorylation occurred at the tyrosine residue.
Insights
Phosphorylation of a 34K cell protein is reduced in Rous sarcoma virus-infected vole cells that have fully reverted. This reduced phosphorylation occurs at tyrosine residues, indicating a link between cell transformation and protein kinase activity.
Area of Science:
- Oncology
- Virology
- Cell Biology
Background:
- Avian retrovirus pp60src is associated with protein kinase activity.
- Rous sarcoma virus (RSV) infection transforms vole cells.
- RSV-infected vole cells can exhibit varying degrees of transformation, including full transformation, partial reversion, and full reversion.
Purpose of the Study:
- To compare the phosphorylation of a 34,000-molecular-weight (34K) cell protein in different states of RSV-induced cell transformation.
- To investigate the role of tyrosine phosphorylation in cell reversion and tumorigenicity.
Main Methods:
- Comparison of 34K protein phosphorylation levels in three types of RSV-infected vole cells: fully transformed, partial revertant, and full revertant.
- Analysis of phosphorylation sites, specifically tyrosine residues.
Main Results:
- Similar amounts of 34K protein were found across all cell types.
- Significantly reduced phosphorylation of the 34K protein was observed in fully reverted vole cells.
- The decreased phosphorylation specifically occurred at tyrosine residues.
Conclusions:
- Phosphorylation of the 34K protein, a potential substrate for pp60src kinase, is diminished in fully reverted vole cells.
- Reduced tyrosine phosphorylation of the 34K protein correlates with the loss of tumorigenicity and normal cell morphology in RSV-infected vole cells.