Molecular Recognition in the P2Y14 Nucleotide Receptor: Probing the Structurally Permissive Terminal Sugar Moiety of Uridine-5′-diphosphoglucose

The P2Y 14 receptor, a nucleotide signaling protein, is activated by uridine-5′-diphosphoglucose 1 and other uracil nucleotides. We have determined that the glucose moiety of 1 is the most structurally permissive region for designing analogues of this P2Y 14 agonist. For example, the carboxylate group of uridine-5′-diphosphoglucuronic acid proved to be suitable for flexible substitution by chain extension through an amide linkage. Functionalized congeners containing terminal 2-acylaminoethylamides prepared by this stratgegy retained P2Y 14 activity, and molecular modeling predicted close proximity of this chain to the 2nd extracellular loop of the receptor. In addition, replacement of glucose with other sugars did not diminish P2Y 14 potency. For example, the [5″]ribose derivative had an EC 50 of 0.24 μM. Selective monofluorination of the glucose moiety indicated a role for the 2″- and 6″-hydroxyl groups of 1 in receptor recognition. The β-glucoside was 2-fold less potent than the native α-isomer, but methylene replacement of the 1″-oxygen abolished activity. Replacement of the ribose ring system with cyclopentyl or rigid bicyclo[3.1.0]hexane groups abolished activity. Uridine-5′-diphosphoglucose also activates the P2Y 2 receptor, but the 2-thio analogue and several of the potent modified-glucose analogues were P2Y 14 -selective.