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 and ARAC10/ROP11. Interacts with PRK6 (PubMed:26961657). Localizes to the apical region of the pollen tube plasma membrane. Expressed in pollen grains and pollen tubes. The PRONE (plant-specific Rop nucleotide exchanger) domain is responsible for the GEF activity. Extended C-terminus.