3μ-phosphoadenosine 5μ-phosphate (PAP) is capable of blocking exoribonucleases (XRNs) activity in the nucleus and cytosol. It stimulates stomatal closure and can serve as a secondary messenger during abscisic acid (ABA) signaling. It is capable of blocking RNA catabolism. Hence it may serve as a physiological modulator of poly (ADP-ribose) polymerase 1 (PARP1) activity.', 'Adenosine 3μ,5μ-diphosphate (PAP) is used to study the kinetics and mechanisms of hydroxysteroid sulfotransferases such as SULT1A1, SULT2A1 of which it is product inhibitor.
