 The N terminal regulatory lobe is responsible for cAMP binding while the C-terminal lobe contains the nucleotide exchange factor activity.At the basal cAMP-free state, EPAC is kept in an auto-inhibitory conformation, in which the N-terminal lobe folds on top of the C-terminal lobe, blocking the active site.Binding of cAMP to EPAC induces a hinge motion between the regulatory and catalytic halves.