IDENTIFICATION OF 6H1 AS A P-2Y PURINOCEPTOR - P2Y(5)

We have determined the identity of the orphan G-protein coupled recept or cDNA, 6H1, present in activated chicken T cells, as a subtype of P- 2Y purinoceptor. This identification is based first on the degree of s equence identity shared with recently cloned members of the P-2Y recep tor family and second on the pharmacological profile. Upon transient e xpression in COS-7 cells the 6H1 receptor bound the radiolabel [S-35]d ATP alpha S specifically and with high affinity (K-d, 10 nM). This spe cific binding could be competitively displaced by a range of ligands a ctive at P-2 purinoceptors, with ATP being the most active (K-i, 116 n M). Such competition studies have established the following rank order of activity: ATP ADP 2-methylthioATP alpha,beta-methyleneATP, UTP, th us confirming 6H1 as a member of the growing family of P-2Y purinocept ors. As the fifth receptor of this type to be identified we suggest th at it be named P2Y(5). (C) 1996 Academic Press, Inc.