Polyoma virus transformation and two-dimensional electrophoresis patterns of baby hamster kidney cell native proteins

The protein extracts of baby hamster kidney cells (BHK 21/C13) before and after malignant transformation by polyoma virus were resolved by isoelectric focusing in the first dimension and electrophoresis on concave 4-24% (w/v) polyacrylamide gradient gels in the second dimension. The resulting two-dimensional patterns were visualised by ultrasensitive silver staining. Major differences were observed in the protein distribution patterns of the two cell lines. Brief trypsinisation of the cells, prior to extraction of cell protein, had little effect upon the protein patterns of BHK cells. Similar treatment of the transformed cells markedly reduced the staining intensity of a string of spots which were present in far greater abundance than in the original BHK cells. The findings suggest that these proteins are located on the surface of the transformed cells and probably under the surface prior to transformation.