López-Corcuera B, Martínez-Maza R, Núñez E, Roux M, Supplisson S, Aragón C
Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma de Madrid, Consejo Superior de Investigaciones Científicas, Spain.
J Neurochem. 1998 Nov;71(5):2211-9. doi: 10.1046/j.1471-4159.1998.71052211.x.
Clonal cell lines stably expressing the glial glycine transporter 1b (GLYT1b) and the neuronal glycine transporter 2 (GLYT2) from rat brain have been generated and used comparatively to examine their kinetics, ion dependence, and electrical properties. Differential sensitivity of the transporters to sarcosine is clearly exhibited by the clonal cell lines. GLYT2 transports glycine with higher apparent affinity than GLYT1b and is not inhibited by any assayed compound, as deduced by glycine transport assays and electrophysiological recordings. A sigmoidal Na+ dependence of the glycine uptake by the stable cell lines is observed, indicating the involvement of more than one Na+ in the transport process. A more cooperative behavior for Na+ of GLYT2 than GLYT1b is suggested. One Cl- is required for GLYT1b and GLYT2 transport cycles, although GLYT1b shows three times higher affinity for this ion than GLYT2. The number of expressed transporters was sufficient to allow electrophysiological recordings of the uptake current in the two stable cell lines. GLYT2 exhibits more voltage dependence in both its glycine-evoked current and its capacitive currents recorded in the absence of substrate.
已构建出稳定表达大鼠脑胶质甘氨酸转运体1b（GLYT1b）和神经元甘氨酸转运体2（GLYT2）的克隆细胞系，并对其动力学、离子依赖性和电特性进行了比较研究。克隆细胞系清楚地显示出转运体对肌氨酸的敏感性差异。通过甘氨酸转运试验和电生理记录推断，GLYT2转运甘氨酸的表观亲和力高于GLYT1b，且不受任何检测化合物的抑制。观察到稳定细胞系对甘氨酸的摄取呈S形的Na⁺依赖性，表明在转运过程中有不止一个Na⁺参与。提示GLYT2对Na⁺的协同作用比GLYT1b更强。GLYT1b和GLYT2的转运循环都需要一个Cl⁻，尽管GLYT1b对该离子的亲和力比GLYT2高3倍。表达的转运体数量足以对两个稳定细胞系中的摄取电流进行电生理记录。GLYT2在其甘氨酸诱发电流和无底物时记录的电容电流中均表现出更强的电压依赖性。
