Functions autonomously, very early in the prespore pathway, to control prespore cell differentiation, maybe at the level of transcription. Also required for proper aggregation. Expressed throughout growth and development with a strong peak of expression at 4 hours when aggregation is initiating. Cells produce large aggregation streams under conditions in which wild-type cells form discrete aggregates. They are unable to induce prespore differentiation, do not express prespore-specific genes and do not produce mature spores. The vast majority of these cells participate in multicellular development and preferentially localize to the very anterior of the slug and form the prestalk and stalk components.