Identification of Determinants Required for Agonistic and Inverse Agonistic Ligand Properties at the ADP Receptor P2Y12
The ADP receptor P2Y 12 belongs to the superfamily of G protein-coupled receptors (GPCRs), and its activation triggers platelet aggregation. Therefore, potent antagonists, such as clopidogrel, are of high clinical relevance in prophylaxis and treatment of thromboembolic events. P2Y 12 displays an elevated basal activity in vitro, and as such, inverse agonists may be therapeutically beneficial compared with antagonists. Only a few inverse agonists of P2Y 12 have been described. To expand this
... ited chemical space and improve understanding of structural determinants of inverse agonist-receptor interaction, this study screened a purine compound library for lead structures using wild-type (WT) human P2Y 12 and 28 constitutively active mutants. Results showed that ATP and ATP derivatives are agonists at P2Y 12 . The potency at P2Y 12 was 2-(methylthio)-ADP . 2-(methylthio)-ATP . ADP . ATP. Determinants required for agonistic ligand activity were identified. Molecular docking studies revealed a binding pocket for the ATP derivatives that is bordered by transmembrane helices 3, 5, 6, and 7 in human P2Y 12, with Y 105 , E 188 , R 256 , Y 259 , and K 280 playing a particularly important role in ligand interaction. N-Methylanthraniloyl modification at the 39-OH of the 29-deoxyribose leads to ligands (mant-deoxy-ATP [dATP], mant-deoxy-ADP) with inverse agonist activity. Inverse agonist activity of mant-dATP was found at the WT human P2Y 12 and half of the constitutive active P2Y 12 mutants. This study showed that, in addition to ADP and ATP, other ATP derivatives are not only ligands of P2Y 12 but also agonists. Modification of the ribose within ATP can result in inverse activity of ATP-derived ligands.