ConoPeptides - G-Protein Coupled Receptors

该项目的长期目标是表征其结构、生化和药理特性。 靶向G蛋白偶联受体(GPCRs)的多肽。在拟议的研究中，我们将重点放在 一种独特的靶向止痛肽Contulakin-G的构效关系研究 神经降压素受体(NTRs)。Contulakin-G是从圆锥蛇毒中分离得到的一种16个残基的多肽 地理位置。该肽与内源性神经肽具有C-末端序列相似性， 神经降压素(NT)，但它也含有一种不寻常的翻译后修饰：苏氨酸的O-糖基化 残留物。Contulakin-G的一个独特的药理特性是，这种非常有效的止痛化合物是一种 神经降压素受体的低亲和力、非去感受性激动剂。与Contulakin-G形成鲜明对比的是，NT 止痛剂的效力是镇痛剂的600倍，但它是一种高亲和力的激动剂，很容易使NTR脱敏。结果： 非糖基化Contulakin-G提示Contulakin-G之间如此深刻的机制差异 而神经降压素可以通过糖基化和不同的N-末端的存在来解释 序列。我们建议系统地探索Contulakin-G和Contulakin-G之间的结构差异 神经降压素决定了这一柯柯多肽的独特药理学特征。这一行动的具体目标 建议包括：(1)化学合成Contulakin-G和神经降压素类似物 糖基结构，(2)Contulakin-G类似物的体外药理性质表征，(3) 人工合成的类似物的镇痛性能及其镇痛机制的评价，(4) 发现与Contulakin-G属于同一基因家族的新成员。 这项研究的结果将使我们能够更好地确定独特的止痛特性的结构决定因素 Contulakin-G，以及检验一种假说，即这种糖肽产生的有效镇痛作用可以在 至少在一定程度上，是因为它不能使神经降压素受体脱敏。长期的结果 这一提议的实施可能导致针对GPCRs的新化合物的开发。

The long-term goal of this project is to characterize structural, biochemical and pharmacological properties of conopeptides that target G-protein coupled receptors (GPCRs). In the proposed research, we will focus on studying structure-activity-relationships of a unique analgesic conopeptide, Contulakin-G, targeting neurotensin receptors (NTRs). Contulakin-G is a 16-residue peptide isolated from venom of Conus geographus. This peptide shares the C-terminal sequence similarity with an endogenous neuropeptide, neurotensin (NT), but it also contains an unusual posttranslational modification: O-glycosylation of a Thr residue. A unique pharmacological property of Contulakin-G is that this very potent analgesic compound is a low-affinity, non-desensetizing agonist for neurotensin receptors. In stark contrast to Contulakin-G, NT is 600-fold less potent as analgesic, but it is a high-affinity agonist that easily desensitizes NTRs. Results with non-glycosylated Contulakin-G suggested that such profound mechanistic differences between Contulakin-G and neurotensin can be accounted for by the presence of both, glycosylation and distinct N-terminal sequences. We propose to systematically explore structural differences between Contulakin-G and neurotensin that determine a unique pharmacological profile of this conopeptide. Specific aims of this proposal include: (1) chemical synthesis of Contulakin-G and neurotensin analogs varying in the peptidic and glycosyl structures, (2) characterization of in vitro pharmacological properties of Contulakin-G analogs, (3) assessment of analgesic properties of the synthesized ananlogs and their mechanism of analgesia, (4) discovery of novel members of the same gene family that Contulakin-G belongs to. Results from the research will allow to better define structural determinants of unique analgesic properties of Contulakin-G, as well as to test a hypothesis that the potent analgesia produced by this glycopeptide can, at least in part, be accounted for by its ability to not desensitize neurotensin receptor. The long-term outcomes of this proposal may lead to development of novel compounds targeting GPCRs.