Guanine-nucleotide exchange factor (GEF) that acts as an activator of Rop (Rho of plants) GTPases by promoting the exchange of GDP for GTP. Interacts with ARAC11/ROP1. Localizes to the apical region of the pollen tube plasma membrane. Expressed in pollen grains. The PRONE (plant-specific Rop nucleotide exchanger) domain is responsible for the GEF activity.