pA-3′-p / pAp

In pA-3′-p phosphate groups are attached to both the ribose 3′ position and the ribose 5′ position of adenosine. This ubiquitous nucleotide is present in almost all organisms. It is a product of 3′-phosphoadenosine 5′-phosphosulfate (PAPS), a cofactor of sulfotransferases (ST / SULTs), and can be used to study the kinetic properties and structure of sulfotransferases. pA-3′-p can also act as an inhibitor of exoribonucleases, such as Xrn1, Rat1p and DXO, and of poly(ADP-ribose) polymerase 1 (PARP-1). Furthermore, it inhibits ADP-induced platelet shape change and aggregation but does not affect ADP-induced inhibition of adenylyl cyclase.