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p53 is associated with a 35 kD protein in cells transformed by simian virus 40
Abstract:
The p53 protein is functionally implicated in the normal control of cell proliferation and, abnormally, in cell transformation. p53 is believed to function via specific cellular target proteins and activated mutants of p53 are associated with proteins of the hsp/hsc 70 heat shock family. However, cellular target proteins of wild type p53 have not, as yet, been described. With the aim of detecting such targets we have screened for cellular protein(s) that co-precipitate with wt p53. We now describe a 35 kD protein co-precipitated with p53 from SV40-transformed cells (a similar protein is detectable in non-viral transformed cells). The 35 kD protein does not appear to be a degradation product of p53. In sequential immunoprecipitations the 35 kD protein was depleted in parallel with p53, with which it appeared to be physically associated. This was substantiated by dissociation experiments in which the 35 kD protein was dissociated under conditions that also dissociate p53 from SV40 large T antigen. Thus wt p53 appears to interact with a cellular protein of 35 kD, the identity of which is under investigation.
Insights
Researchers identified a 35 kD protein that physically associates with wild-type p53 (wt p53). This discovery sheds light on the normal function of p53 in cell proliferation and transformation.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- The p53 protein regulates cell proliferation and is implicated in cell transformation.
- Wild-type p53 (wt p53) is known to interact with cellular targets, but these have not been identified.
- Activated p53 mutants associate with heat shock proteins, but wt p53 targets remain elusive.
Purpose of the Study:
- To identify cellular target proteins that physically interact with wild-type p53 (wt p53).
- To characterize the association between wt p53 and potential target proteins.
Main Methods:
- Co-precipitation assays to detect proteins binding to wt p53.
- Sequential immunoprecipitation to assess protein depletion and association.
- Dissociation experiments to analyze the stability of protein complexes.
Main Results:
- A 35 kD protein was consistently co-precipitated with wt p53 from SV40-transformed cells.
- This 35 kD protein is not a degradation product of p53.
- Sequential immunoprecipitation and dissociation experiments confirmed a stable physical association between wt p53 and the 35 kD protein.
Conclusions:
- Wild-type p53 (wt p53) physically interacts with a specific 35 kD cellular protein.
- This interaction is stable and suggests a functional role for the 35 kD protein in p53 pathways.
- Further investigation is required to determine the identity and function of this novel wt p53-interacting protein.