May be involved in the regulation of pollen-tube growth. Monomer. Specifically expressed in pollen. Causes an allergic reaction in human (PubMed:10224228, PubMed:30150373). Binds to IgE of sensitized grass pollen allergic patients (PubMed:10224228, PubMed:30150373). Triggers immediate hypersensitivity reactions by cross-linking receptor-bound IgE molecules on effector cells, and induces degranulation of basophils sensitized with IgE (PubMed:30150373). Recombinant protein induces basophil histamine release and immediate type skin reactions in sensitized allergic patients (PubMed:10224228).