To design and synthesize bivalent ligands for adenosine A1âdopamine D1 receptor heteromers (A1âD1R), and evaluate their pharmacological activities. Bivalent ligands and their corresponding A1R monovalent ligands were designed and synthesized. The affinities of the bivalent ligands for A1R and D1R in rat brain membrane preparation were examined using radiolabeled binding assays. To demonstrate the formation of A1âD1R, fluorescence resonance energy transfer (FRET) was conducted in HEK293 cells transfected with D1-CFP and A1-YFP. Molecular modeling was used to analyze the possible mode of protein-protein and protein-ligand interactions. Two bivalent ligands for A1R and D1R (20a, 20b), as well as the corresponding A1R monovalent ligands (21a, 21b) were synthesized. In radiolabeled binding assays, the bivalent ligands showed affinities for A1R 10â100 times higher than those of the corresponding monovalent ligands. In FRET experiments, the bivalent ligands significantly increased the heterodimerization of A1R and D1R compared with the corresponding monovalent ligands. A heterodimer model with the interface of helixes 3, 4, 5 of A1R and helixes 1, 6, 7 from D1R was established with molecular modeling. The distance between the two ligand binding sites in the heterodimer model was approximately 48.4 Ã
, which was shorter than the length of the bivalent ligands. This study demonstrates the existence of A1âD1R in situ and a simultaneous interaction of bivalent ligands with both the receptors.
设计并合成
腺苷A1-
多巴胺D1受体异聚体(A1-D1R)的双价
配体,并评估其药理活性。设计并合成了双价
配体及其相应的A1R单价
配体。使用放射性标记的结合试验,检测了双价
配体在大鼠脑膜制备物中对A1R和D1R的亲和力。为了证明A1-D1R的形成,在转染了D1-CFP和A1-YFP的HEK293细胞中进行了荧光共振能量转移(FRET)。使用分子建模分析了可能的蛋白质-蛋白质和蛋白质-
配体相互作用模式。合成了两种A1R和D1R的双价
配体(20a, 20b)及其相应的A1R单价
配体(21a, 21b)。在放射性标记的结合试验中,双价
配体对A1R的亲和力比相应的单价
配体高出10-100倍。在FRET实验中,与相应的单价
配体相比,双价
配体显著增加了A1R和D1R的异源二聚化。通过分子建模建立了一个异源二聚体模型,该模型在A1R的螺旋3、4、5和D1R的螺旋1、6、7之间有界面。在异源二聚体模型中,两个
配体结合位点之间的距离约为48.4 Å,比双价
配体的长度短。这项研究证明了A1-D1R在体内的存在以及双价
配体与两个受体的同时相互作用。