May act in concert with RAB3A in regulating aspects of synaptic vesicle membrane flow within the nerve terminal. EHBP1L1. The GTP bound form of RAB15 interacts with REP15. Interacts (GTP-bound form) with MICAL1, MICAL3, MICALCL, EHBP1 and EHBP1L1. Belongs to the small GTPase superfamily. Rab family.