A SINGLE AMINO-ACID DETERMINES THE SUBUNIT-SPECIFIC SPIDER TOXIN BLOCK OF ALPHA-AMINO-3-HYDROXY-5-METHYLISOXAZOLE-4-PROPIONATE KAINATE RECEPTOR CHANNELS
A SINGLE AMINO-ACID DETERMINES THE SUBUNIT-SPECIFIC SPIDER TOXIN BLOCK OF ALPHA-AMINO-3-HYDROXY-5-METHYLISOXAZOLE-4-PROPIONATE KAINATE RECEPTOR CHANNELS
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DOI：
10.1073/pnas.90.14.6528
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发表时间：
1993-07-15
影响因子：
11.1
通讯作者：
KONNERTH, A
中科院分区：
文献类型：
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作者：
BLASCHKE, M;KELLER, BU;KONNERTH, A
Joro spider toxin （JSTX）是无脊椎动物和脊椎动物谷氨酸能AMPA/KA （α -氨基-3-羟基-5-甲基异恶唑-4-丙酸/海因酸盐）受体通道最有效的拮抗剂之一。对某些类型的谷氨酸能突触有不同的阻断作用。通过使用蜘蛛毒素的合成模拟物，研究人员已经证明，平行和攀爬纤维突触输入到大鼠小脑浦肯野神经元。通过研究JSTX作用于爪蟾卵母细胞中表达的重组AMPA/KA受体GluR1-GluR4和GluR6的分子基础，我们发现亚微摩尔浓度的JSTX具有亚基特异性阻断作用。因此，形成具有线性电流-电压（I-V）关系的受体通道的受体亚基（GluR1/2、GluR2/3和GluR6）不受影响，而具有纠正I-V关系的受体亚基（GluR1、GluR3、GluR4和GluR1/3）被JSTX可逆阻断。通过使用位点定向诱变获得的受体亚基突变体，我们已经确定了一个单一的氨基酸位置（谷氨酰胺在第二跨膜结构域），这对JSTX阻断至关重要。由于该位点先前已被证明控制AMPA/KA受体通道的I-V关系，并参与调节通道对钙离子的通透性，我们的研究结果表明JSTX结合剂量到通道的中心孔区。
Joro spider toxin (JSTX) is one of the most potent antagonists of glutamatergic AMPA/KA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate) receptor channels in invertebrates and vertebrates. A differential blocking effect on certain types of glutamatergic synapses-e.g., parallel and climbing fiber synaptic inputs to rat cerebellar Purkinje neurons-has been shown by using a synthetic analog of the spider toxin. By investigating the molecular basis of the JSTX action on the recombinant AMPA/KA receptors GluR1-GluR4 and GluR6 expressed in Xenopus oocytes, we found that submicromolar concentrations of JSTX exert a subunit-specific block. Thus, receptor subunits forming a receptor channel with a linear current-voltage (I-V) relationship (GluR1/2, GluR2/3, and GluR6) were not affected, while receptor subunits with rectifying I-V relationships (GluR1, GluR3, GluR4, and GluR1/3) were reversibly blocked by JSTX. By using receptor-subunit mutants obtained by site-directed mutagenesis, we have identified a single amino acid position (glutamine in the proposed second transmembrane domain) that is critical for the JSTX block. Since this site has previously been shown to control the I-V relationship of the AMPA/KA receptor channel and to participate in the regulation of the channel's permeability for calcium ions, our findings suggest that JSTX binds dose to the central pore region of the channel.