Center for Membrane Biology, Department of Biochemistry and Molecular Biology, Graduate School of Biomedical Sciences, University of Texas Health Science Center, Houston, Texas 77030, USA.
J Biol Chem. 2011 May 13;286(19):16953-7. doi: 10.1074/jbc.M111.224576. Epub 2011 Mar 24.
The conformational changes in the agonist binding domain of the glycine-binding GluN1 and glutamate-binding GluN2A subunits of the N-methyl D-aspartic acid receptor upon binding agonists of varying efficacy have been investigated by luminescence resonance energy transfer (LRET) measurements. The LRET-based distances indicate a cleft closure conformational change at the GluN1 subunit upon binding agonists; however, no significant changes in the cleft closure are observed between partial and full agonists. This is consistent with the previously reported crystal structures for the isolated agonist binding domain of this receptor. Additionally, the LRET-based distances show that the agonist binding domain of the glutamate-binding GluN2A subunit exhibits a graded cleft closure with the extent of cleft closure being proportional to the extent of activation, indicating that the mechanism of activation in this subunit is similar to that of the glutamate binding α-amino-5-methyl-3-hydroxy-4-isoxazole propionate and kainate subtypes of the ionotropic glutamate receptors.
通过荧光共振能量转移（LRET）测量研究了配体效力不同的激动剂与甘氨酸结合 GluN1 和谷氨酸结合 GluN2A 亚基的 NMDA 受体结合时激动剂结合域构象的变化。基于 LRET 的距离表明，激动剂结合时 GluN1 亚基的裂隙闭合构象发生变化；然而，部分激动剂和完全激动剂之间没有观察到裂隙闭合的明显变化。这与先前报道的该受体分离的激动剂结合域晶体结构一致。此外，基于 LRET 的距离表明，谷氨酸结合 GluN2A 亚基的激动剂结合域表现出渐变的裂隙闭合，裂隙闭合的程度与激活的程度成正比，表明该亚基的激活机制与离子型谷氨酸受体的谷氨酸结合α-氨基-5-甲基-3-羟基-4-异恶唑丙酸和 kainate 亚型相似。
