Suramin (SRM)

Suramin is also used in research as a broad-spectrum antagonist of P2 receptors and agonist of Ryanodine receptors. Its effect on telomerase has been investigated. It may have some activity against RNA viruses. In addition to antagonism of P2 receptors, Suramin inhibits the activation of heterotrimeric G proteins in a variety of other GPCRs with varying potency. It prevents the association of heteromeric G proteins and therefore the receptors Guanine exchange functionality (GEF). With this blockade the GDP will not release from the Gα subunit so it can not be replaced by a GTP and become activated. This has the effect of blocking downstream G protein mediated signaling of various GPCR proteins including Rhodopsin, the A1 Adenosine receptor, and the D2 dopamine receptor. Suramin contains eight benzene rings, four of which are fused in pairs (naphthalene), four amide groups in addition to the one of urea and six sulfonate groups.