Involved in the regulation of gamete interactions during the double fertilization and to prevent multiple-pollen tube attraction; mediates the redistribution of the gamete fusogen HAP2/GCS1 to the cell surface after secretion upon sperm arrival. Secreted via vesicle exocytose upon sperm arrival, especially in the apical region of the degenerating synergid cell. Restricted to female reproductive tissues, specifically accumulating in storage vesicles of the unfertilized egg cell. Confined to the egg cell before fertilization, but disappears upon gamete fusion. Also present in zygotes and early embryos. Belongs to the plant egg cell-secreted peptide family. Extended C-terminus.