Cell surface charge and regulation of cell division of 3T3 cells and transformed derivatives.

The cell surface charge of 3T3, 3T6, SV40-3T3 cells and trypsin-, neuraminidase- and serumtreated preparations of these has been characterized by microcell electrophoresis. At 25 °C, density-inhibited 3T3 cells show a decrease in electrophoretic mobility when treated with various stimuli of cell division. This effect is not observed at 25 °C for transformed derivatives. The surface charge configuration of various cell preparations exhibits a thermal transition which is located within a temperature range characteristic of each preparation. These and other results from cell electrophoresis, taken together with those obtained in agglutination studies by other authors, are considered evidence for the occurrence in the plasma membrane of these cells of a twodimensional phase separation. The temperature range of this phase separation is shifted on treating the cells by growth stimuli. This effect might be an indication of a basic trigger mechanism in the cell cycle.