The role of protein interaction motifs in regulating the polarity and clustering of the metabotropic glutamate receptor mGluR1a
The role of protein interaction motifs in regulating the polarity and clustering of the metabotropic glutamate receptor mGluR1a
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DOI：
10.1523/jneurosci.1015-06.2006
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发表时间：
2006-08-02
影响因子：
5.3
通讯作者：
Banker, Gary A.
中科院分区：
文献类型：
--
作者：
Das, Sonal S.;Banker, Gary A.
当在培养的海马神经元中表达时，代谢型谷氨酸受体mGluR 1a被极化为树突并集中在突触后位点。我们使用突变分析来确定先前在mGluR 1a C末端识别的蛋白质相互作用基序如何有助于其定位。我们的研究结果表明，介导与荷马家族蛋白质的相互作用的聚脯氨酸基序是至关重要的mGluR 1a的突触簇。一个单一的点突变，在这个基序，防止荷马与mGluR 1a的结合，减少其与突触后标记的共定位到近机会的水平，但不影响其树突极性。与此相反，删除PDZ（突触后密度-95/椎间盘大/occludens-1）结合结构域，与Tamalin和柄相互作用，对突触定位没有影响。这些蛋白质相互作用基序都不是重要的运输到质膜或极化树突。虽然删除mGluR 1a的整个C末端仅适度降低其树突极性，但该结构域足以将未极化的报告蛋白重定向至树突。这些观察结果表明，mGluR 1a含有冗余的树突靶向信号。总之，我们的研究结果表明，mGluR 1a的本地化涉及两个不同的步骤，一个目标蛋白质树突和第二个隔离它在突触后位点;不同的蛋白质相互作用基序介导的每一步。
When expressed in cultured hippocampal neurons, the metabotropic glutamate receptor mGluR1a is polarized to dendrites and concentrated at postsynaptic sites. We used a mutational analysis to determine how previously identified protein interaction motifs in the C terminus of mGluR1a contribute to its localization. Our results show that the polyproline motif that mediates interaction with Homer family proteins is critical for the synaptic clustering of mGluR1a. A single point mutation in this motif, which prevents the binding of Homer with mGluR1a, reduced its colocalization with a postsynaptic marker to near-chance levels but did not affect its dendritic polarity. In contrast, deleting the PDZ ( postsynaptic density-95/Discs large/zona occludens-1) binding domain, which interacts with Tamalin and Shank, had no effect on synaptic localization. Neither of these protein interaction motifs is important for trafficking to the plasma membrane or for polarization to dendrites. Although deleting the entire C terminus of mGluR1a only modestly reduced its dendritic polarity, this domain was sufficient to redirect an unpolarized reporter protein to dendrites. These observations suggest that mGluR1a contains redundant dendritic targeting signals. Together, our results indicate that the localization of mGluR1a involves two distinct steps, one that targets the protein to dendrites and a second that sequesters it at postsynaptic sites; different protein interactions motifs mediate each step.