Two-dimensional electrophoresis of membrane proteins from normal and transformed cells

Abstract

We have compared cell surface proteins and glycoproteins from normal and transformed cells by two-dimensional electrophoresis. The tumor lines studied include viral and spontaneous transformants which cause tumors that either regress, or grow progressively and kill the host. After the cells were labeled, crude membranes were prepared, and their protein components were resolved by two-dimensional electrophoresis. Cells were labeled with either [35S]methionine, [14C]glucosamine, or 125I-lactoperoxidase. This allows comparison of cell-cell differences in surface structure as well as membrane proteins and glycoproteins. We have demonstrated that not all transformed cell lines give a characteristic "transformed" protein pattern. Many of the differences between the normal and transformed cell protein patterns may be related to alterations in the carbohydrate of membrane glycoproteins. A correlation can be made between the patterns obtained for cell lines and the immunogenicity and tumorigenicity of these cells in vivo.