Extraction of membrane factors that inhibit aggregation in Dictyostelium discoideum

Plasma membrane preparations partially inhibit the reaggregation of dissociated aggregation-component cells of Dictyostelium discoideum, and membranes from aggregation-competent cells are more inhibitory than membranes from vegetative cells. Inhibitory activity can be extracted from the membranes of aggregation-competent cells with the detergent octyl glucoside or with EDTA, although the inhibition is never more than partial. Extracts of vegetative membranes have relatively little inhibitory activity and the amount of inhibitory activity that can be extracted increases as cells become aggregation-competent. The inhibitory activity is sensitive to Pronase, but relatively stable to heat. Inhibitory activity can also be extracted from intact aggregation-competent cells by 20 mM-EDTA or 0.25% octyl glucoside.