The conformational change of a murine temperature-sensitive p53 protein is independent of a change in phosphorylation status.
Wild-type and mutant p53 proteins exhibit opposing activities in respectively suppressing and promoting tumour development. In a rat embryo fibroblast cell line transformed with a murine temperature-sensitive p53 gene, p53 functions as a oncogene at 37 degrees C and as a tumour suppressor at 32 degrees C [Michalovitz, D., Halevy, O. & Oren, M. (1990). Cell, 62, 671-680]. We have used this cell line to investigate whether this temperature-dependent switching of function involves changes in the phosphorylation of p53 protein. Monoclonal antibodies PAb246 and PAb240 were used to immunoprecipitate metabolically 32P-labelled p53 protein in the 'wild-type' or mutant conformation from cells grown at 32 degrees C or 37 degrees C. Tryptic phosphopeptide maps were prepared from the isolated 'wild-type' and mutant p53 proteins. At 32 degrees C and 37 degrees C phosphopeptide maps of the 'wild-type' and mutant protein were identical. This demonstrates that the temperature-dependent conformation change, and associated functional change, in the p53 protein does not involve a change in the state of phosphorylation.
Picksley
S M
SM
CRC Cell Transformation Group, Department of Biochemistry, Dundee University, UK.
Meek
D W
DW
Lane
D P
DP
D000818:Animals; D002461:Cell Line, Transformed; D010449:Peptide Mapping; D010766:Phosphorylation; D011233:Precipitin Tests; D011487:Protein Conformation; D051381:Rats; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism*
D016159:Tumor Suppressor Protein p53