Componement of the CCZ1-MON1 RAB7A guanine exchange factor (GEF). Acts as a positive regulator of CCZ1-MON1A/B function necessary for endosomal/autophagic flux and efficient RAB7A localization. Found in a complex with RMC1, CCZ1, MON1A and MON1B. Highly expressed in heart, brain, spleen, lung, liver, skeletal muscle, kidney and testis. Belongs to the RMC1 family.