Functions as downstream effector of Rho-related GTP binding proteins of the 'Rho of Plants' (ROPs) family. Participates in the propagation of ROP GTPase signals in specific cellular responses. Functions as downstream effector of ARAC11/ROP1 to activate calcium signaling that leads to F-actin disassembly associated with exocytosis in the tip of the growing pollen tube. Counteracts the ARAC11/ROP1-RIC4 pathway, which promotes apical F-actin assembly associated with vesicle accumulation, to control actin dynamics and pollen tube apical growth. Interacts with ARAC11/ROP1. Expressed in flowers and pollen. Over-expression of RIC3 in tobacco germinating pollen induces depolarized pollen tube growth.