Female gametophyte-specific component of the signaling pathway required for fertilization. Required for reception of the pollen tube by the female gametophyte (PubMed:19028964, PubMed:26052747, PubMed:27081182). Acts specifically at the synergid cell surface for pollen tube reception (PubMed:26052747, PubMed:27081182). Plays a role in double fertilization and early seed development (PubMed:20163554). Component of the FER-regulated Rho GTPase signaling complex. Acts as a chaperone and coreceptor for FER. Required for localization of FER to the plasma membrane (PubMed:26052747). Interacts with FER. Localized to the filiform apparatus of the synergid cell. Expressed in leaves, buds, flowers and stems (PubMed:19028964). Highest expression in the synergid cells of the female gametophyte (PubMed:19028964, PubMed:26052747). Expressed only in fully differentiated cells of the egg apparatus. Not detected in developing ovules undergoing megasporogenesis or megagametogenesis (PubMed:19028964). Expressed in unfertilized, mature ovules (PubMed:20163554). Failure of pollen tube arrest and fertilization. Deficient in pollen tube reception by the female gametophyte.