Localizes in orbicules, walls, nucleus and to condensed dormant structures in the cytoplasm of the mature nonhydrated pollen grains. Upon germination, localizes in mitochondria, nucleus, endoplasmic reticulum, Golgi cisterns and vesicles, vacuoles, lipid inclusions and the intine wall. Expressed in pollen. Expressed during dehydration, dormancy, air dispersion, hydrated preactivated and germination stages. In hydrated pollen grains, expressed in discarded exine, the exudates, and the orbicules. Expressed in developing lamellate structures of the microspore cell cytoplasm. By air pollution. Causes an allergic reaction in human. Binds to IgE in 63% of 104 patients allergic to cypress pollen. Belongs to the thaumatin family.