Hechler B, Cazenave J P, Hanau D, Gachet C
INSERM Unite 311, Biologie et Pharmacologie des Interactions du Sang avec les Vaisseaux et les Biomateriaux, Strasbourg, France.
Nouv Rev Fr Hematol (1978). 1995;37(4):231-40.
The platelet receptor for ADP has been classified as a P2 purinoceptor of the P2T type where ADP is the natural agonist and ATP a competitive antagonist. Since the P2T receptor seems to be specific to platelets, we investigated the possibility that the human megakaryoblastic cell line Meg-01 might express the platelet ADP receptor, using functional studies and the ADP analogue [33P]2MeSADP as a specific P2T radioligand. ADP and 2MeSADP were able to induce shape change and pseudopod formation in Meg-01 cells. [33P]2MeSADP binding to membrane preparations was saturable and specific, binding sites being of high affinity (Kd = 13 +/- 3 nM) and present at a concentration of 13 +/- 7 fmoles/mu g protein. In contrast to UTP and GTP, ADP and ATP were able to displace the specific [33P]2MeSADP binding. ADP, 2MeSADP, UTP and ATP induced a dose dependent increase in intracellular calcium concentration. Desensitization experiments demonstrated that UTP, and ADP share a common P2U purinoceptor and that Meg-01 cells also express a P2T purinoceptor for which ADP and 2MeSADP are agonists and ATP a competitive antagonist. It was concluded that the human megakaryoblastic cell line Meg-01 expresses two distinct types of functional P2 receptor; a P2U and a P2T purinoceptor. This cell line could therefore provide the necessary material to clone the as yet unidentified platelet P2T purinoceptor.
ADP的血小板受体已被归类为P2T型的P2嘌呤受体，其中ADP是天然激动剂，ATP是竞争性拮抗剂。由于P2T受体似乎对血小板具有特异性，我们利用功能研究以及ADP类似物[33P]2MeSADP作为特异性P2T放射性配体，研究了人巨核母细胞系Meg-01可能表达血小板ADP受体的可能性。ADP和2MeSADP能够诱导Meg-01细胞发生形态改变和伪足形成。[33P]2MeSADP与膜制剂的结合具有饱和性和特异性，结合位点具有高亲和力（Kd = 13 +/- 3 nM），且以13 +/- 7飞摩尔/微克蛋白质的浓度存在。与UTP和GTP不同，ADP和ATP能够取代特异性的[33P]2MeSADP结合。ADP、2MeSADP、UTP和ATP诱导细胞内钙浓度呈剂量依赖性增加。脱敏实验表明，UTP和ADP共享一个共同的P2U嘌呤受体，并且Meg-01细胞还表达一种P2T嘌呤受体，对于该受体，ADP和2MeSADP是激动剂，ATP是竞争性拮抗剂。得出的结论是，人巨核母细胞系Meg-01表达两种不同类型的功能性P2受体；一种P2U和一种P2T嘌呤受体。因此，该细胞系可为克隆尚未鉴定的血小板P2T嘌呤受体提供必要的材料。
