CHANGES IN THE PLASMA-MEMBRANE ATPASE ACTIVITY IN RELATIONSHIP TO CELL-PROLIFERATION IN DICTYOSTELIUM

The plasma membrane ATPase activity of Dictyostelium amoebae increases ca 2.5 fold from non dividing stationary phase cells to synchronously growing cells. This increase in ATPase activity takes place during the three hours lag period that precede the cell division after diluting stationary cells into fresh medium and is prevented by cycloheximide. No differences in the Km for ATP or in the optimal pH for activity were observed in kinetic studies carried out with purified plasma membranes from stationary and proliferating cells.