The effects of inhibition of development in Dictyostelium discoideum on changes in plasma membrane composition and topography

Previous experiments have demonstrated that during the development of the cellular slime mold, Dictyostelium discoideum, the macromolecular composition of the plasma membrane changes dramatically. In addition, the exposure on the external face of the plasma membrane of some developmentally conserved polypeptides varies during development. When development and differentiation were prevented with cycloheximide or mutation, the bulk of the changes in composition were prevented. These treatments also prevented the disappearance of macromolecules and were particularly effective in preventing changes of glycoprotein composition. Similarly, the program of developmental changes of exposure of polypeptide was disrupted by both treatments. Cycloheximide, but not the mutation, stimulated the premature disappearance of six external polypeptides. This may reflect a rapid turnover of these polypeptides, which cannot be replaced in the absence of protein synthesis.