Boyer J L, Harden T K
Department of Pharmacology, University of North Carolina, School of Medicine, Chapel Hill 27599.
Mol Pharmacol. 1989 Dec;36(6):831-5.
3'-O-(4-Benzoyl)benzoyladenosine 5'-triphosphate (BzATP), a photoaffinity analog of ATP, was used as a ligand for the phospholipase C-linked P2Y-purinergic receptor in turkey erythrocytes. In membranes from [3H]inositol-labeled turkey erythrocytes, BzATP stimulated inositol phosphate formation in a concentration-dependent manner (K0.5 = 172 +/- 4 nM). The effect of BzATP was strictly dependent on the presence of guanine nucleotides and was not additive with the effect of other full P2Y-purinergic receptor agonists. Photolysis of [3H]-inositol-labeled membranes in the presence of BzATP had no effect on the magnitude of the maximally attainable response of phospholipase C to the P2Y-purinergic receptor agonist adenosine 5'-O-(2-thiodiphosphate) (ADP beta S) plus guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S). However, the effects of submaximally effective concentrations of GTP gamma S were markedly increased in membranes previously photolyzed in the presence of BzATP. In addition, the rate of activation of phospholipase C by GTP gamma S in membranes photolyzed in the presence of BzATP was increased 3-fold, as compared with control membranes. BzATP effects on phospholipase C were prevented by photolysis in the presence of ATP or ADP, but not by the presence of the weak P2Y-purinergic receptor agonist beta,gamma-methyleneadenosine 5'-triphosphate. These results suggest that BzATP is a full P2Y-purinergic receptor agonist, which after photolysis becomes irreversibly associated with turkey erythrocyte membranes and promotes P2Y-purinergic receptor-mediated guanine nucleotide-dependent activation of phospholipase C.
3'-O-(4-苯甲酰基)苯甲酰腺苷5'-三磷酸（BzATP）是ATP的一种光亲和类似物，被用作火鸡红细胞中与磷脂酶C相关的P2Y嘌呤能受体的配体。在[3H]肌醇标记的火鸡红细胞膜中，BzATP以浓度依赖的方式刺激肌醇磷酸的形成（K0.5 = 172 +/- 4 nM）。BzATP的作用严格依赖于鸟嘌呤核苷酸的存在，并且与其他完全的P2Y嘌呤能受体激动剂的作用无相加性。在BzATP存在下对[3H] - 肌醇标记的膜进行光解，对磷脂酶C对P2Y嘌呤能受体激动剂腺苷5'-O-(2-硫代二磷酸)（ADPβS）加鸟苷5'-O-(3-硫代三磷酸)（GTPγS）的最大可达到反应的幅度没有影响。然而，在先前于BzATP存在下光解的膜中，次最大有效浓度的GTPγS的作用明显增强。此外，与对照膜相比，在BzATP存在下光解的膜中GTPγS对磷脂酶C的激活速率增加了3倍。在ATP或ADP存在下进行光解可阻止BzATP对磷脂酶C的作用，但弱P2Y嘌呤能受体激动剂β,γ-亚甲基腺苷5'-三磷酸的存在则不能阻止。这些结果表明，BzATP是一种完全的P2Y嘌呤能受体激动剂，光解后与火鸡红细胞膜不可逆结合，并促进P2Y嘌呤能受体介导的鸟嘌呤核苷酸依赖性磷脂酶C激活。
