Structure and Function of CB2 Cannabinoid Receptor

描述（由申请人提供）：本研究计划的长期目标是确定CB2大麻素受体功能的分子基础。为达到这一目的，将采取以下步骤。在目标1和目标2中，将进行相互作用诱变、分子模型和新化合物测试研究。这种结合的方法提高了我们的理解，并且应该继续揭示大麻素配体如何被受体识别，受体亚型选择性的起源，以及这些受体如何被激活/灭活的新见解。大麻素受体共享许多在其他研究充分的G蛋白偶联受体（gpcr）中看到的保守序列基序，如视紫红质和生物胺受体。然而，大麻素受体中缺少一些螺旋弯曲残基和基序，以及许多其他gpcr中存在的关键二硫桥。在Aim 3中，CB2大麻素受体的两个跨膜结构域的配体结合缝隙暴露将使用取代半胱氨酸可及性方法进行映射。这种方法应该阐明大麻素受体这些跨膜结构域序列分化的结构和功能后果。

DESCRIPTION (provided by applicant): The long-term goal of this research proposal is to identify the molecular basis underlying the functions of the CB2 cannabinoid receptor. To achieve this purpose, the following steps will be taken. In Aim 1 and 2, the interactive mutagenesis, molecular modeling and new compound testing studies will be carried out. This combined approach has advanced our understanding, and should continue to reveal new insights on how cannabinoid ligands are recognized by their receptors, the origin of receptor subtype-selectivity, and how these receptors are activated/inactivated. Cannabinoid receptors share many of the conserved sequence motifs seen in other well-studied G protein-coupled receptors (GPCRs), such as rhodopsin and biogenic amine receptors. However, several helix-bending residues and motifs, and a key disulfide bridge present in many other GPCRs are missing in cannabinoid receptors. In Aim 3, Ligand binding crevice exposure of two transmembrane domains of CB2 cannabinoid receptor will be mapped using substituted-cysteine accessibility method. This approach should elucidate structural and functional consequences of the sequence divergence in these trasmembrane domains of cannabinoid receptors. In Aim 4, Disulfide bond formation of CB2 receptor will be determined directly by the state-of-art methodologies of mass spectrometry. Investigating the unique disulfide bond or absence of a disulfide bond should provide important helix folding information of CB2 receptor, and this will have important implications regarding ligand binding crevice and activation mechanisms of this receptor. Finally, in Aim 5, effort will be devoted to over-express and purify large amounts of functional CB2 receptor. This challenging task, if successfully completed, should have a significant impact by providing the badly needed pure receptor proteins for future high-resolution biophysical studies. Overall, This study should help us to understand in more molecular detail the structure and function of CB2 receptor. CB2 is primarily distributed in the immune system. It is very important for the immune-modulatory effects of marijuana. In the long run, this study should also help us to develop better cannabinoid mimetics for the treatment of immune system illnesses, such as inflammation and autoimmune diseases. The drugs that specifically targeted at CB2 should be devoid of psvchoactive side effects of marijuana.