This work has produced a series of molecular models of the protein EPAC1 in three distinct functional states (inactive, intermediate, and active). We note that the partitioning of conformational space between inactive and intermediate states is somewhat arbitrary. The distance between G269 and residues 279-281 was used here to describe the changes in PBC conformation. Other descriptors, such as change in the activator pocket volume could have been used. It is therefore advisable to assess detailed probability distribution plots build from selected features such as in Figure before further simplifying protein dynamics to two or three macrostates. However the exact geometric boundaries between the intermediate state and active/inactive states is less significant for developing full activators since the active/inactive state partitioning is much clearer. cAMP, as well as the interruption of said activation by the L273W mutation (Figure ). The MSMs allow quantification of the effects of ligands on protein conformational preferences, and output equilibrium conformational ensembles that can be interrogated to support design hypotheses. The dynamics of these ensembles confirm the previously reported dual action of cAMP, that is the change in PBC conformation and stabilization of active state via the lid region. Comparison of the WT EPAC1 and EPAC1 L273W ensembles also confirms that the mutation decouples the PBC from the hinge, but does not interfere with cAMP binding. The mutated W273 residue does not shift out of the space between the hinge and the PBC to allow for stabilization of a disordered hinge C-terminus, and also actively stabilizes the helical conformation of the hinge through π-stacking interactions with F300 (Figure and).