For other salt forms please inquire. 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 (Dichtel et al. 1997, Yun et al. 2018), and of poly(ADP-ribose) polymerase 1 (PARP-1) (Toledano et al. 2012). Furthermore, it inhibits ADP-induced platelet shape change and aggregation but does not affect ADP-induced inhibition of adenylyl cyclase (Hechler et al. 1998). References: Dichtel et al., EMBO J., 16, 7184 - 7195  (1997); Hechler et al., Blood, 92, 152 - 159 (1998); Toledano et al., Biochem. J., 443, 485 - 490 (2012); Yun et al., Biochem. Biophys. Res. Commun., 504, 89 - 95 (2018).