Extracellular signal peptide that regulates cell fate. Seed endosperm. Expressed specifically in the embryo surrounding region at the micropylar end of the seed endosperm at early stages (4 to 7 days after pollination, DAP) and ever-decreasing parts of the suspensor at subsequent stages (at protein level). The O-glycosylation (arabinosylation) of the hydroxyproline Pro-85 enhances binding affinity of the ESR2p peptide for its receptor. Belongs to the CLV3/ESR signal peptide family.