Exchange protein directly activated by cAMP – Ras-related protein Rap-1b interface (Epac–Rap1b interface)

The Epac–Rap1b interface represents the physical and functional interaction site between the Exchange Protein directly Activated by cAMP (Epac) and the small GTPase Ras-related protein Rap-1b. Epac proteins, specifically Epac1 (RAPGEF3) and Epac2 (RAPGEF4), function as guanine nucleotide exchange factors (GEFs) that catalyze the conversion of Rap1b from an inactive GDP-bound state to an active GTP-bound state in response to elevated intracellular cAMP levels (UniProt: O95398, P61224). This signaling axis is a critical regulator of diverse cellular processes, including integrin-mediated cell adhesion, E-cadherin-mediated cell-cell junctions, and exocytosis (PubMed: 10608546). In pathological contexts, dysregulation of the Epac–Rap1b interface is implicated in cancer progression, particularly in promoting metastasis and cell migration, as well as in cardiovascular disorders like heart failure and vascular leak (PubMed: 23341447). Therapeutic targeting of this interface aims to disrupt the recruitment or activation of Rap1b by Epac, offering a more specific approach than global cAMP modulation. Small molecule inhibitors such as ESI-09 have been developed to block this interaction, providing potential avenues for treating malignancies and inflammatory conditions where Epac-mediated signaling is overactive (PubMed: 23341447).

Other names

Epac-Rap1b complexRAPGEF3-RAP1B interfaceRAPGEF4-RAP1B interfaceEpac1-Rap1b interfaceEpac2-Rap1b interface

Inhibition of guanine nucleotide exchange by disrupting the physical interaction or stabilizing the inactive conformation of the Epac-Rap1b complex, thereby preventing the conversion of Rap1b from its GDP-bound to its GTP-bound state.