Related Experiment Videos
Phosphorylation of specific sites in the gag-myc polyproteins encoded by MC29-type viruses correlates with their
Abstract:
The putative transforming proteins of the four acute leukaemia viruses belonging to the MC29 subgroup were shown to be phosphorylated in vivo. Comparison of the MC29 and CM11 encoded phosphoproteins revealed identical tryptic phosphopeptide maps, with both the gag and myc domains being phosphorylated. In contrast, the MH2 phosphoprotein was only phosphorylated on the gag domain. Analysis of partial transformation-defective MC29 deletion mutants revealed that the deletions had removed the v-myc specific phosphopeptides. Phosphoamino acid analysis showed that these deleted phosphopeptides were phosphorylated on threonine. Moreover, a back mutant that had regained transforming ability had regained these phosphopeptides. These studies correlate the phosphorylation of the gag-myc protein with the transformation capability of the virus.
Insights
Phosphorylation of gag-myc proteins in acute leukemia viruses is crucial for their transforming ability. Studies show specific phosphopeptides, particularly on threonine, correlate directly with viral transformation capability.
Area of Science:
- Oncology
- Virology
- Molecular Biology
Background:
- Acute leukemia viruses, particularly the MC29 subgroup, possess putative transforming proteins.
- Phosphorylation is a key post-translational modification influencing protein function.
Purpose of the Study:
- To investigate the phosphorylation patterns of transforming proteins from MC29 subgroup acute leukemia viruses.
- To correlate specific phosphorylation events with viral transformation capability.
Main Methods:
- In vivo phosphorylation analysis of viral proteins.
- Tryptic phosphopeptide mapping and phosphoamino acid analysis.
- Analysis of transformation-defective deletion mutants and back mutants.
Main Results:
- MC29 and CM11 viruses showed phosphorylation in both gag and myc domains, while MH2 phosphorylated only gag.
- Deletions in MC29 mutants removed v-myc specific phosphopeptides, which were phosphorylated on threonine.
- Reversion to transforming ability restored these specific phosphopeptides.
Conclusions:
- The phosphorylation of the gag-myc protein is directly correlated with the transformation capability of these acute leukemia viruses.
- Specific threonine phosphorylation within the v-myc domain is critical for viral oncogenesis.