Tamalin, a PDZ domain-containing protein, links a protein complex formation of group 1 metabotropic glutamate receptors and the guanine nucleotide exchange factor cytohesins
Tamalin, a PDZ domain-containing protein, links a protein complex formation of group 1 metabotropic glutamate receptors and the guanine nucleotide exchange factor cytohesins
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DOI：
10.1523/jneurosci.22-04-01280.2002
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发表时间：
2002-02-15
影响因子：
5.3
通讯作者：
Nakanishi, S
中科院分区：
文献类型：
--
作者：
Kitano, J;Kimura, K;Nakanishi, S
在这项调查中，我们报告的95 kDa的突触后密度蛋白（PSD-95）/光盘大/ ZO-1（PDZ）域包含蛋白质称为tamalin，最近也命名为GRP 1相关支架蛋白（GRASP），与组1代谢型谷氨酸受体（mGluRs）相互作用的鉴定和表征。酵母双杂交系统和体外下拉试验表明，PDZ结构域，氨基末端的一半Tamalin直接结合到I类PDZ结合基序组1 mGluRs。Tamalin的C-末端的一半也与细胞粘连素结合，细胞粘连素是特异性针对ADP-核糖基化因子（ARF）家族的小GTP结合蛋白的鸟嘌呤核苷酸交换因子（GEF）的成员。Tamalin mRNA主要在端脑区域表达，并与第1组mGluR mRNA的表达高度重叠。两个tamalin和cytohesin-2的富集和共分布与mGluR 1a在突触后膜组分。重要的是，重组和天然mGluR 1a/tamalin/cytohesin-2复合物共免疫沉淀转染COS-7细胞和大鼠脑组织，分别。转染tamalin和突变体tamalin缺乏细胞粘连蛋白结合结构域引起的增加和减少mGluR 1a在COS-7细胞的细胞表面表达，分别。此外，腺病毒介导的表达tamalin和显性阴性tamalin促进和减少内源性mGluR 5在培养的海马神经元的神经炎分布，分别。结果表明，Tamalin在与ARF特异性GEF蛋白的第1组mGluRs的关联中起着关键作用，并有助于细胞内运输和突触处第1组mGluRs的大分子组织。
In this investigation, we report identification and characterization of a 95 kDa postsynaptic density protein (PSD-95)/discs-large/ ZO-1 (PDZ) domain-containing protein termed tamalin, also recently named GRP1-associated scaffold protein (GRASP), that interacts with group 1 metabotropic glutamate receptors (mGluRs). The yeast two-hybrid system and in vitro pull-down assays indicated that the PDZ domain-containing, amino-terminal half of tamalin directly binds to the class I PDZ-binding motif of group 1 mGluRs. The C-terminal half of tamalin also bound to cytohesins, the members of guanine nucleotide exchange factors (GEFs) specific for the ADP-ribosylation factor (ARF) family of small GTP-binding proteins. Tamalin mRNA is expressed predominantly in the telencephalic region and highly overlaps with the expression of group 1 mGluR mRNAs. Both tamalin and cytohesin-2 were enriched and codistributed with mGluR1a in postsynaptic membrane fractions. Importantly, recombinant and native mGluR1a/tamalin/cytohesin-2 complexes were coimmunoprecipitated from transfected COS-7 cells and rat brain tissue, respectively. Transfection of tamalin and mutant tamalin lacking a cytohesin-binding domain caused an increase and decrease in cell-surface expression of mGluR1a in COS-7 cells, respectively. Furthermore, adenovirus-mediated expression of tamalin and dominant-negative tamalin facilitated and reduced the neuritic distribution of endogenous mGluR5 in cultured hippocampal neurons, respectively. The results indicate that tamalin plays a key role in the association of group 1 mGluRs with the ARF-specific GEF proteins and contributes to intracellular trafficking and the macromolecular organization of group 1 mGluRs at synapses.