ConoPeptides - G-Protein Coupled Receptors

该项目的长期目标是表征靶向G蛋白偶联受体(GPCRs)的椰子多肽的结构、生化和药理学特性。在拟议的研究中，我们将重点研究一种独特的止痛肽Contulakin-G的结构-活性-关系，靶向 神经降压素受体(NTRs)。Contulakin-G是从地理圆锥蛇毒中分离得到的一种16个残基的多肽。这种多肽与一种内源性神经肽神经降压素(NT)有相似的C末端序列，但它也包含一个不寻常的翻译后修饰：Thr残基的O-糖基化。Contulakin-G的一个独特的药理学特性是，这种非常有效的止痛化合物是一种低亲和力的非去感受性神经降压素受体激动剂。与Contulakin-G形成鲜明对比的是，NT的止痛剂效力比Contulakin-G低600倍，但它是一种高亲和力的激动剂，很容易使NTRs脱敏。结果： 非糖基化的Contulakin-G提示Contulakin-G和神经降压素之间如此深刻的机制差异可以通过两者的糖基化和不同的N-末端序列的存在来解释。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。这项建议的具体目标包括：(1)化学合成不同肽和糖基结构的Contulakin-G和神经降压素类似物，(2)Contulakin-G类似物的体外药理性质表征，(3) (4)Contulakin-G所属基因家族新成员的发现。研究结果将有助于更好地确定Contulakin-G独特止痛特性的结构决定因素，并验证由这种糖肽产生的有效止痛可以在 至少在一定程度上，是因为它不能使神经降压素受体脱敏。这一提议的长期结果可能导致针对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.