Rap guanine nucleotide exchange factor 4 (EPAC2)

Rap guanine nucleotide exchange factor 4 (EPAC2, encoded by the RAPGEF4 gene) is a multi-domain intracellular protein directly activated by cyclic AMP (cAMP) and acts as a guanine nucleotide exchange factor (GEF) for the small GTPases Rap1 and Rap2[1][2][4][5][6]. EPAC2 transduces the cAMP signal independently of protein kinase A (PKA), regulating a range of essential cellular processes. It is abundantly expressed in the brain, neuroendocrine, and endocrine tissues, notably in pancreatic β-cells, where it amplifies insulin secretion in response to glucose and hormonal stimuli in a cAMP-dependent manner[1][4]. EPAC2 is involved in neurotransmitter release, neuronal differentiation, synaptic plasticity, and exocytosis of secretory granules[1][4]. Dysregulation or abnormal expression of EPAC2 has been implicated in diseases such as diabetes, certain cancers (e.g., glioma), cardiac arrhythmia, and neuropsychiatric conditions[4][7]. Selective small-molecule agonists and antagonists have been developed as pharmacological tools to study EPAC2 and to explore its therapeutic potential, although no EPAC2-targeted drugs have yet entered clinical use[3][8].

Other names

Exchange protein directly activated by cAMP 2RAPGEF4EPAC2cAMP-regulated guanine nucleotide exchange factor 2

Agonist/Activator: Small molecules (e.g., cAMP analogs, S-220, S-280) that bind EPAC2, inducing conformational change and promoting the exchange of GDP for GTP on Rap1 and Rap2 GTPases[3][7]. Antagonist/Inhibitor: Compounds (e.g., ESI-05, ESI-07) bind to EPAC2 and prevent activational conformational changes, blocking downstream Rap GEF activity[8].