Related Experiment Videos
p37mos-associated serine/threonine protein kinase activity correlates with the cellular transformation function of
Abstract:
A serine/threonine-specific protein kinase activity is closely associated with v-mos-encoded proteins. Experiments were conducted with several mutant forms of p37mos to determine whether or not the kinase function correlates with the biological activity of the mutant v-mos genes. Two mutants lacking cell transformation activity, one an arginine substitution for lysine-121 in the putative ATP-binding site and the other a 23-amino acid deletion from the C-terminal end of p37mos, had no kinase activity associated with their mutant proteins. However, a third mutant with reduced biological activity had drastically less kinase activity than the wild-type protein. The latter mutant was able to phosphorylate the kinase-inactive p37mos(Arg-121) protein in vitro. These results indicate that even though p37mos(Arg-121) can be phosphorylated in trans by other kinase molecules, it lacks the ability to phosphorylate itself in vitro. This provides a compelling argument that the protein kinase function of p37mos is an intrinsic property of the protein. Moreover, since the kinase function correlates with the cellular transformation activity of the v-mos gene, we predict that it is required for the biological activity of the v-mos gene.
Insights
The v-mos protein kinase activity is essential for its biological function in cell transformation. Mutants lacking kinase activity also lack cell transformation ability, indicating kinase function is intrinsic and required for v-mos gene activity.
Area of Science:
- Molecular Biology
- Oncogenesis
- Protein Kinase Research
Background:
- The v-mos gene product, p37mos, exhibits serine/threonine-specific protein kinase activity.
- This kinase activity is thought to be closely linked to the oncogenic potential of v-mos.
Purpose of the Study:
- To investigate the correlation between the protein kinase function of p37mos and its biological activity in cellular transformation.
- To determine if kinase activity is an intrinsic property of p37mos.
Main Methods:
- Site-directed mutagenesis was used to create several mutant forms of p37mos.
- Mutants were analyzed for protein kinase activity and their ability to induce cell transformation.
- In vitro phosphorylation assays were performed using wild-type and mutant p37mos proteins.
Main Results:
- Mutants lacking cell transformation activity also lacked detectable kinase activity.
- A mutant with reduced biological activity showed significantly decreased kinase activity.
- The kinase-inactive p37mos(Arg-121) mutant could be phosphorylated in trans but not in cis, suggesting intrinsic kinase function.
Conclusions:
- The protein kinase function of p37mos is an intrinsic property of the protein.
- Kinase activity is required for the v-mos gene's ability to induce cellular transformation.
- These findings highlight the critical role of p37mos kinase activity in oncogenesis.