Cell electrophoresis of the cellular slime mould Dictyostelium discoideum. I. Characterization of some of the cell surface ionogenic groups.

The reduction in cell surface charge density during the early stages of differentiation of the cellular slime mould, Dictyostelium discoideum, has been studied by the technique of cell electrophoresis. Using specific chemical reagents, it was shown that the cell surface negative charge was probably due to side chain carboxyl groups of proteins. During differentiation, there was a decrease in the density of these groups, accompanied by an increase in that of amino groups. The significance of this finding is discussed in relation to cell surface structure and cell differentiation.