Chemical Synapses - Biophysical Studies

本项目研究半胱氨酸环受体超家族分子的结构和功能：肌肉 烟碱乙酰胆碱受体（nAChR）、神经元α 4 β 2 nAChR和5-羟色胺5-HT 3 受体的假设1指出在激动剂结合位点按以下顺序发生三个事件， (a)激动剂的带电荷的胺/铵基团被胆甾醇-β-D受体吸引到该位点。 与侧链上固定负电荷的相互作用，（B）对于具有氨基的激动剂（不是a 季铵基团），这种相互作用通过与季铵基团的主链羰基的H-键来稳定。 149-150肽键，（c）最早的构象变化使激动剂处于阳离子-π相互作用， 色氨酸α 149。假设2指出，M2-M3接头经历骨架变化， 门控期间的构象。假设3指出，在通道激活过程中，所有五个通道的上M2螺旋 亚基相对于相邻的螺旋重新定向。假设4指出，动态，历史- α 4 β 2和P2 X2受体之间的依赖性功能相互作用通过β 2-M3-M4环发生 和P2 X2的C末端尾部。假设1和2将通过宏观和单通道进行检验 带有非天然氨基酸侧链和非天然氨基酸侧链的受体的电生理学评估 主链连接。假设1、3和4将在基于以下物质的直接荧光的测量中进行测试： 栓系探针、荧光共振能量转移（FRET）和基于镧系元素的共振能量 转移（LRET）。关于乙酰胆碱受体和5-HT 3受体的知识可能会提供 病理生理学的见解和更好的药物治疗，包括戒烟在内的健康挑战， 帕金森氏病，阿尔茨海默氏病，疼痛，克罗恩氏病，婴儿猝死综合征，注意 缺陷障碍、常染色体显性夜间额叶癫痫和精神分裂症。

This project studies the structure and function of molecules in the Cys-loop receptor superfamily: the muscle nicotinic acetylcholine receptor (nAChR), the neuronal alpha4beta2 nAChR, and the serotonin 5-HT3 receptor. Hypothesis 1 states that three events occur in the following sequence at the agonist binding site, (a) The charged amine / ammonium group of the agonist is attracted to the site by a monopole-monopole interaction with fixed negative.charges on side chains, (b) For agonists with an amino group (not a quaternary ammonium group), this interaction is stabilized by an H-bond to the backbone carbonyl of the 149-150 peptide bond, (c) The earliest conformational change places the agonist in a cation-pi interaction at tryptophan alpha149. Hypothesis 2 states that ye M2-M3 linker undergoes a change in backbone conformation during gating. Hypothesis 3 states that during channel activation, the upper M2 helix of all five subunits re-orients with respect to neighboring helices. Hypothesis 4 states that the dynamic, history- dependent functional interaction between alpha4beta2 and P2X2 receptors occurs via the beta2-M3-M4 loop and the P2X2 C-terminal tail. Hypotheses 1 and 2 will be tested with macroscopic and single-channel electrophysiological assessments of receptors bearing unnatural amino-acid side chains and unnatural backbone linkages. Hypotheses 1, 3, and 4 will be tested in measurements based on direct fluorescence of tethered probes, fluorescence resonance energy transfer (FRET), and lanthanide-based resonance energy transfer (LRET). The resulting knowledge about acetylcholine receptors and 5-HT3 receptors may provide both pathophysiological insights and better drug therapies for health challenges including smoking cessation, Parkinson's disease, Alzheimer's disease, pain, Crohn's disease, sudden infant death syndrome, attention deficit disorder, autosomal dominant nocturnal frontal lobe epilepsy, and schizophrenia.