Identification of amino acid residues responsible for the α5 subunit binding selectivity of L-655,708, a benzodiazepine binding site ligand at the GABAA receptor
Identification of amino acid residues responsible for the α5 subunit binding selectivity of L-655,708, a benzodiazepine binding site ligand at the GABAA receptor
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DOI：
10.1046/j.1471-4159.2001.00289.x
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发表时间：
2001-04-01
影响因子：
4.7
通讯作者：
Hadingham, KL
中科院分区：
文献类型：
--
作者：
Casula, MA;Bromidge, FA;Hadingham, KL
L-655，708是γ-氨基丁酸A型（GABA（A））受体苯二氮卓类位点的配体，与含α 1受体相比，对含α 5受体的亲和力高100倍。分子生物学方法已被用于确定α 5亚基中的哪些残基负责这种选择性。已经鉴定了两种氨基酸，α 5Thr 208和α 5Ile 215，它们各自赋予配体约10倍的结合选择性，并且它们一起导致该配体对含α 5受体的亲和力高100倍。L-655，708是GABA（A）受体的部分反向激动剂，在含α 1和含α 5受体之间未显示出功能选择性，并且对含α 1亚单位的受体（其中两个位点的氨基酸均已改变为其α 5对应物（α 1 Delta Ser 205-Thr，Val 212-lie））的效力未显示出变化。除了决定L-655，708的结合选择性外，这些氨基酸残基还影响许多其他苯并二氮杂卓（BZ）位点配体的结合亲和力。因此，它们是GABA（A）受体的BZ位点的重要元件，并且进一步描绘了正好位于受体α亚基的第一跨膜结构域的N-末端的区域，该区域有助于该结合位点。
L-655,708 is a ligand for the benzodiazepine site of the gamma -aminobutyric acid type A (GABA(A)) receptor that exhibits a 100-fold higher affinity for alpha5-containing receptors compared with alpha1-containing receptors. Molecular biology approaches have been used to determine which residues in the alpha5 subunit are responsible for this selectivity. Two amino acids have been identified, alpha 5Thr208 and alpha 5lle215, each of which individually confer approximately 10-fold binding selectivity for the ligand and which together account for the 100-fold higher affinity of this ligand at a5-containing receptors. L-655,708 is a partial inverse agonist at the GABA(A) receptor which exhibited no functional selectivity between alpha1- and alpha5-containing receptors and showed no change in efficacy at receptors containing alpha1 subunits where amino acids at both of the sites had been altered to their alpha5 counterparts (alpha1 Delta Ser205-Thr,Val212-lie). In addition to determining the binding selectivity of L-655,708, these amino acid residues also influence the binding affinities of a number of other benzodiazepine (BZ) site ligands. They are thus important elements of the BZ site of the GABA(A) receptor, and further delineate a region just N-terminal to the first transmembrane domain of the receptor alpha subunit that contributes to this binding site.