Hirata M, Hayashi Y, Ushikubi F, Yokota Y, Kageyama R, Nakanishi S, Narumiya S
Department of Pharmacology, Kyoto University Faculty of Medicine, Japan.
Nature. 1991 Feb 14;349(6310):617-20. doi: 10.1038/349617a0.
Thromboxane A2 is a very unstable arachidonate metabolite, yet a potent stimulator of platelet aggregation and a constrictor of vascular and respiratory smooth muscles. It has been implicated as a mediator in diseases such as myocardial infarction, stroke and bronchial asthma. Using a stable analogue of this compound we recently purified the human platelet thromboxane A2 receptor to apparent homogeneity. Using an oligonucleotide probe corresponding to its partial amino-acid sequence, we have obtained a complementary DNA clone encoding this receptor from human placenta and a partial clone from cultured human megakaryocytic leukaemia cells. The placenta cDNA encodes a protein of 343 amino acids with seven putative transmembrane domains. The protein expressed in COS-7 cells binds drugs with affinities identical to those of the platelet receptor, and that in Xenopus oocytes opens Ca2(+)-activated Cl- channel on agonist stimulation. Northern blot analysis and nucleotide sequences of the two clones suggest that an identical species of the thromboxane A2 receptor is present in platelets and vascular tissues. This first report on the molecular structure of an eicosanoid receptor will promote the molecular pharmacology and pathophysiology of these bioactive compounds.
血栓素A2是一种极不稳定的花生四烯酸代谢产物，但却是血小板聚集的强效刺激剂以及血管和呼吸道平滑肌的收缩剂。它被认为是心肌梗死、中风和支气管哮喘等疾病的介质。我们最近利用该化合物的一种稳定类似物将人血小板血栓素A2受体纯化至表观均一性。通过使用与其部分氨基酸序列相对应的寡核苷酸探针，我们从人胎盘中获得了编码该受体的互补DNA克隆，并从培养的人巨核细胞白血病细胞中获得了部分克隆。胎盘cDNA编码一个含有7个推定跨膜结构域的343个氨基酸的蛋白质。在COS-7细胞中表达的该蛋白质与药物结合的亲和力与血小板受体相同，并且在非洲爪蟾卵母细胞中，激动剂刺激时会打开Ca2(+)激活的Cl-通道。对这两个克隆的Northern印迹分析和核苷酸序列表明，血小板和血管组织中存在相同种类的血栓素A2受体。这篇关于类二十烷酸受体分子结构的首次报道将推动这些生物活性化合物的分子药理学和病理生理学研究。
