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A major phosphoprotein of cells infected with pseudorabies virus is phosphorylated by cellular casein kinase II
Abstract:
Endogenous protein phosphorylation was studied in extracts of hamster fibroblasts infected with pseudorabies virus. The major phosphorylation was detected quite late in infection and involved an acidic protein of Mr 62,000. It was catalysed by an enzyme activity with the properties of cellular casein kinase II. Two-dimensional gel analysis was used to demonstrate that this same protein was also phosphorylated in vivo. The phosphoprotein was detected in mature virions and is most likely viral in origin.
Insights
Pseudorabies virus infection triggers late-stage phosphorylation of a 62,000 Mr protein in hamster cells. This phosphorylation, mediated by casein kinase II, occurs both in vitro and in vivo, with the protein found in mature virions.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Understanding viral protein modification is crucial for deciphering infection mechanisms.
- Endogenous protein phosphorylation plays a key role in cellular regulation and viral pathogenesis.
Purpose of the Study:
- To investigate endogenous protein phosphorylation in hamster fibroblasts during pseudorabies virus infection.
- To identify the specific protein(s) involved and the enzymatic activity responsible for phosphorylation.
Main Methods:
- Cellular extracts from infected hamster fibroblasts were analyzed for protein phosphorylation.
- Enzyme activity was characterized using biochemical assays.
- Two-dimensional gel electrophoresis was employed to analyze protein phosphorylation in vivo and in vitro.
- Analysis of mature virions for the presence of phosphoproteins.
Main Results:
- A major phosphorylation event was observed late in pseudorabies virus infection.
- The primary phosphoprotein identified has a molecular mass of 62,000 Mr and is acidic.
- The phosphorylation was catalyzed by an enzyme exhibiting characteristics of cellular casein kinase II.
- This protein was confirmed to be phosphorylated both in vitro and in vivo.
- The phosphoprotein was detected in mature pseudorabies virions, suggesting a viral origin.
Conclusions:
- Pseudorabies virus infection induces late-stage phosphorylation of a specific 62,000 Mr protein.
- Cellular casein kinase II is likely responsible for this phosphorylation event.
- The phosphoprotein is incorporated into mature virions, indicating its potential role in the viral life cycle.