Hollmann M, Maron C, Heinemann S
Molecular Neurobiology Laboratory, Salk Institute, La Jolla, California 92037.
Neuron. 1994 Dec;13(6):1331-43. doi: 10.1016/0896-6273(94)90419-7.
We investigated the transmembrane topology of the glutamate receptor GluR1 by introducing N-glycosylation sites as reporter sites for an extracellular location of the respective site. Our data show that the N-terminus is extracellular, whereas the C-terminus is intracellular. Most importantly, we found only three transmembrane domains (designated TMD A, TMD B, and TMD C), which correspond to the previously proposed TMDs I, III, and IV, respectively. Contrary to earlier models, the putative channel-lining hydrophobic domain TMD II does not span the membrane, but either lies in close proximity to the intracellular face of the plasma membrane or loops into the membrane without transversing it. Furthermore, the region between TMDs III and IV, in previous models believed to be intracellular, is an entirely extracellular domain.
我们通过引入N-糖基化位点作为各位点细胞外定位的报告位点，研究了谷氨酸受体GluR1的跨膜拓扑结构。我们的数据表明，N端位于细胞外，而C端位于细胞内。最重要的是，我们仅发现了三个跨膜结构域（分别命名为TMD A、TMD B和TMD C），它们分别对应于先前提出的跨膜结构域I、III和IV。与早期模型相反，推测的形成通道内衬的疏水结构域TMD II并不跨越细胞膜，而是紧邻质膜的细胞内表面，或者环入膜内但不穿过膜。此外，在先前模型中认为位于细胞内的TMD III和TMD IV之间的区域是一个完全位于细胞外的结构域。
