P2Y₁ receptor signaling is controlled by interaction with the PDZ scaffold NHERF-2

P2Y₁ purinergic receptors (P2Y₁Rs) mediate rises in intracellular Ca²⁺ in response to ATP, but the duration and characteristics of this Ca²⁺ response are known to vary markedly in distinct cell types. We screened the P2Y₁R carboxyl terminus against a recently created proteomic array of PDZ (PSD-95/Drosophila Discs large/ZO-1 homology) domains and identified a previously unrecognized, specific interaction with the second PDZ domain of the scaffold NHERF-2 (Na⁺/H ⁺ exchanger regulatory factor type 2). Furthermore, we found that P2Y₁R and NHERF-2 associate in cells, allowing NHERF-2-mediated tethering of P2Y₁R to key downstream effectors such as phospholipase Cβ. Finally, we found that coexpression of P2Y₁R with NHERF-2 in glial cells prolongs P2Y₁R-mediated Ca²⁺ signaling, whereas disruption of the P2Y₁R-NHERF-2 interaction by point mutations attenuates the duration of P2Y₁R-mediated Ca²⁺ responses. These findings reveal that NHERF-2 is a key regulator of the cellular activity of P2Y₁R and may therefore determine cell-specific differences in P2Y₁R-mediated signaling.