Structure and Function of the Acetylcholine Receptor

我们研究的长期目标是了解神经递质受体如何在健康和疾病状态下运作。我们已经选择了乙酰胆碱受体（AChR）在运动突触检查这类蛋白质的基本功能：神经递质的结合触发开放的内在离子通道。为了理解这种结合-触发过程，我们建议（i）确定α和非α亚基中的残基，这些残基在结合到通道的开放和闭合状态时稳定ACh，（ii）确定AChR如何维持均匀的通道门控动力学，（iv）确定先天性肌无力综合征（CMS）潜在突变的机制后果，（iv）确定在主要胞外结构域中界定推定的二级结构的保守残基是否有助于AChR活化和（v）确定AChR的主要胞外结构域的结构特征。该方法结合了定点诱变和哺乳动物细胞中的表达，单通道记录和动力学分析，配体结合和蛋白质生物化学的测量。完成拟议的研究将推进我们对运动终板的突触传递和药物作用的理解，促进神经肌肉疾病（如CMS）的治疗，而一般的发现将为神经递质受体超家族的其他成员提供结构功能关系的见解。

The long-term aim of our research is to understand how receptors for neurotransmitters operate in health and disease states. We have chosen the acetylcholine receptor (AChR) at the motor synapse to examine the essential function of this class of proteins: binding of neurotransmitter triggering opening of an intrinsic ion channel. Toward understanding this binding-triggering process, we propose to (i) identify residues in a and non-a subunits that stabilize ACh when bound to open and closed states of the channel, (ii) determine how the AChR maintains uniform channel gating kinetics, (iv) determine mechanistic consequences of mutations underlying congenital myasthenic syndromes (CMS), (iv) determine whether conserved residues bounding putative secondary structures in the major extracellular domain contribute to AChR activation and (v) determine structural features of the major extracellular domain of the AChR. The approach combines site-directed mutagenesis and expression in mammalian cells, single channel recording and kinetic analysis, measurements of ligand binding and protein biochemistry. Completion of the proposed studies will advance our understanding of synaptic transmission and drug action at motor endplates, facilitate treatment of neuromuscular disorders such as CMS, while the general findings will provide insight into structure function relationships for other members of the neurotransmitter receptor superfamily.