FIG. 1.

Illustration of the regulation of PKA RIα phase separation by different binding partners. Binding of two cAMP molecules (red) per RIα subunit (blue) leads to dissociation (and activation) of PKA_cat (green). The increased disorder in the RIα linker region [between the N-terminal dimerization and docking (D/D) domain in oval and tandem cAMP-binding domains in rectangle] and the action of the dissociated PKA_cat promote the formation of phase-separated bodies (highlighted on the right with a dotted boundary). In contrast, PKA_cat in the absence of cAMP suppresses RIα phase separation by binding to and rigidifying RIα (shown on the left). For clarity, only a half of a holoenzyme, consisting of a single PKA_cat subunit and a single RIα subunit, is illustrated.