A novel chloride-dependent L-[3H]glutamate binding site in astrocyte membranes.
A novel chloride-dependent L-[3H]glutamate binding site in astrocyte membranes.
复制标题
星形胶质细胞膜中新型氯依赖性 L-[3H]谷氨酸结合位点。
DOI：
10.1111/j.1471-4159.1987.tb05727.x
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发表时间：
1987
影响因子：
4.7
通讯作者：
Cotman,CW
中科院分区：
文献类型：
--
作者：
Bridges,RJ;Nieto-Sampedro,M;Kadri,M;Cotman,CW
从培养的星形胶质细胞制备的膜组分显示出与L-[~3H]谷氨酸-塔玛酸的特异性结合部位，该结合部位依赖于Cl-−，不依赖于Na+。该结合部位为单一饱和结合部位，aKD约为0.5μM，可被天冬氨酸L、天冬氨酸L和喹乙醇抑制，对红藻氨酸、N-甲基-D-天冬氨酸、α-氨基-3-羟基-5-甲基-4-异恶唑丙酸酯和2-氨基-4-磷酸不敏感。结合部位的药理学特征表明，它不同于以前在突触膜制剂中描述的任何部位。然而，离子需求、配体特异性和抑制剂敏感性的比较表明，所描述的结合是依赖于Cl-−的高亲和力谷氨酸摄取系统的第一步。这种结合研究提供了一个有用的模型系统，用于研究兴奋性氨基酸与星形胶质细胞之间的密切联系，通过高亲和力摄取终止谷氨酸的兴奋作用，以及酸性氨基酸在单细胞类型的膜上的兴奋毒性作用。
Membrane fractions prepared from astrocytes grown in culture exhibit a specific binding site for L‐[3H]glu‐tamate that is Cl−‐dependent and Na+‐independent. The binding site is a single saturable site with aKDof about 0.5 μM, is inhibited by L‐aspartate, L‐cysteate, and quisqualate, and is insensitive to kainate,N‐methyl‐D‐aspartate, α‐ami‐no‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionate, and 2‐ami‐no‐4‐phosphonobutyrate. The pharmacological characteristics of the binding site indicate that it is distinct from any site previously described in synaptic membrane preparations. Comparisons of ionic requirements, ligand specificity, and inhibitor sensitivities, however, suggest the described binding is the first step in a Cl−‐dependent high‐affinity glutamate uptake system. Such binding studies provide a useful model system in which to investigate the close association between excitatory amino acids, astrocytes, the termination of glutamate's excitatory action by high‐affinity uptake, and the excitotoxic action of acidic amino acids in membranes of a single cell type.