domain:The DEP domain is involved in membrane localization independent from regulation by cAMP.,domain:The N-terminal nucleotide phosphate binding region cAMP 1 has a much lower affinity for cAMP as compared to cAMP 2.,function:Guanine nucleotide exchange factor (GEF) for RAP1A, RAP1B and RAP2A small GTPases that is activated by binding cAMP. Seems not to activate RAB3A. Involved in cAMP-dependent, PKA-independent exocytosis through interaction with RIMS2.,similarity:Contains 1 DEP domain.,similarity:Contains 1 N-terminal Ras-GEF domain.,similarity:Contains 1 Ras-GEF domain.,similarity:Contains 2 cyclic nucleotide-binding domains.,subunit:Interacts with RIMS1 and RIMS2. Probably part of a complex with RIMS2 and GTP-activated RAB3A.,tissue specificity:Predominantly expressed in brain and adrenal gland. Isoform 2 is expressed in liver. Isoform 1 is expressed in liver at very low levels.,