Unknown. Required for development but not for cell death. Self-associates; the interaction is calcium-independent Interacts with pefa; the interaction is calcium-dependent. Interacts with pefb; the interaction is calcium-dependent. Colocalizes to large vesicle-like structures with chmp4. Colocalizes with vamp7A to endosomes but not to lysosomes. No obvious effect on unicellular growth but induces a premature development arrest, with an inability to differentiate spores and to build a true stalk indicative of a major defect in differentiation and morphogenesis. The abortive structure contains a mixture of undifferentiated cells and vacuolated stalk-like cells. Differing results include abnormal development only at very low extracellular Ca(2+) conditions (below 10 nM) (PubMed:15276209) or at alkaline pH (pH 9) (PubMed:15757670).