Human 5'-NT und P2X receptors: Structure, function and inhibitor design

除了作为细胞能量载体的主要作用外，ATP还具有作为细胞外信号物质的重要功能。在这些嘌呤能信号通路中，ATP与P2 X或P2 Y受体结合。信号传导作用由核苷酸酶终止，核苷酸酶将ATP逐步脱磷酸化为腺苷。在本项目中，人P2 X受体和酶外-5-核苷酸酶（E-5 -NT）的空间结构将通过X射线晶体学确定。通过这些结构研究，我们的目标是表征酶和受体的分子机制，并有助于合理设计特异性抑制剂。对于人类5 -NT单晶已经生长，适合于结构测定。P2 X受体的结构研究应通过受体胞外域的表达、纯化和结晶来实现。最近确定的第一个X-射线结构的全长P2 X4从斑马鱼表明，大ATP结合胞外域参与密集接触的同源三聚体受体。该结构表明，单独的胞外域作为三聚体是稳定的，并且它适合于研究ATP结合，特别是ATP相关激动剂和拮抗剂的结合。

In addition to its major role as a cellular energy carrier, ATP also has an important function as an extracellular signaling substance. In these purinergic signaling pathways, ATP binds to P2X or P2Y receptors. The signaling action is terminated by nucleotidases, which stepwise dephosphorylate ATP to adenosine. Within this project spatial structures of human P2X receptors and of the enzyme ecto-5 -nucleotidase (E-5 -NT) shall be determined by X-ray crystallography. Via these structural studies we aim to characterize the molecular mechanism of the enzyme and the receptors and to contribute to a rational design of specific inhibitors. For human 5 -NT single crystals have been grown, that are suitable for structure determination. The structural studies of P2X receptors shall be achieved via expression, purification and crystallization of the ectodomains of the receptors. The recently determined first X-ray structure of full-length P2X4 from zebrafish shows that the large ATP-binding ectodomain is involved in intensive contacts in the homotrimeric receptor. The structure suggests that the ectodomain alone is stable as a trimer und that it is suitable to study ATP binding and especially the binding of pharmacologically relevant agonists and antagonists.