Synonyms:DENN/MADD domain containing 3, DENND3, KIAA0870 Background:Guanine nucleotide exchange factor(GEF) activating RAB12. Promotes the exchange of GDP to GTP, converting inactive GDP-bound RAB12 into its active GTP-bound form. Thereby, may play a role in protein transport from recycling endosomes to lysosomes regulating, for instance, the degradation of the transferrin receptor.