Molecular cloning and characterization of rat P2Y4 nucleotide receptor

Abstract

An intronless open reading frame encoding a protein (361aa in length) was isolated from a rat genomic library probed with a DNA fragment from rat heart. This protein showed 83% sequence identity with the human P2Y 4 (hP2Y 4) receptor and represents a homologue of the human pyrimidinoceptor. However, the rP2Y 4 receptor is not selective for uridine nucleotides and, instead, shows an agonist potency order of ITP=ATP=ADP(pure)=UTP=ATPγS=2‐MeSATP=Ap 4 A>UDP(pure). ADP, ATPγS, 2‐MeSATP and UDP are partial agonists. Thus, in terms of agonist profile, rP2Y 4 is more like the P2U receptor subtype. The rP2Y 4 receptor was reversibly antagonized by Reactive blue 2 but not by suramin which, otherwise, inhibits the hP2Y 2 receptor (a known P2U receptor). Thus, rP2Y 4 and the P2Y 2 subtype appear to be structurally distinct forms of the P2U receptor (where ATP and UTP are equi‐active) but can be distinguished as suramin‐insensitive and suramin‐sensitive P2U receptors, respectively.