Chiu Joanna C, Brenner Eric D, DeSalle Rob, Nitabach Michael N, Holmes Todd C, Coruzzi Gloria M
Department of Biology, New York University , New York 10003, USA.
Mol Biol Evol. 2002 Jul;19(7):1066-82. doi: 10.1093/oxfordjournals.molbev.a004165.
The ionotropic glutamate receptor (iGluR) gene family has been widely studied in animals and is determined to be important in excitatory neurotransmission and other neuronal processes. We have previously identified ionotropic glutamate receptor-like genes (GLRs) in Arabidopsis thaliana, an organism that lacks a nervous system. Upon the completion of the Arabidopsis genome sequencing project, a large family of GLR genes has been uncovered. A preliminary phylogenetic analysis divides the AtGLR gene family into three clades and is used as the basis for the recently established nomenclature for the AtGLR gene family. We performed a phylogenetic analysis with extensive annotations of the iGluR gene family, which includes all 20 Arabidopsis GLR genes, the entire iGluR family from rat (except NR3), and two prokaryotic iGluRs, Synechocystis GluR0 and Anabaena GluR. Our analysis supports the division of the AtGLR gene family into three clades and identifies potential functionally important amino acid residues that are conserved in both prokaryotic and eukaryotic iGluRs as well as those that are only conserved in AtGLRs. To begin to investigate whether the three AtGLR clades represent different functional classes, we performed the first comprehensive mRNA expression analysis of the entire AtGLR gene family. On the basis of RT-PCR, all AtGLRs are expressed genes. The three AtGLR clades do not show distinct clade-specific organ expression patterns. All 20 AtGLR genes are expressed in the root. Among them, five of the nine clade-II genes are root-specific in 8-week-old Arabidopsis plants.
离子型谷氨酸受体（iGluR）基因家族在动物中已得到广泛研究，并被确定在兴奋性神经传递和其他神经元过程中发挥重要作用。我们之前在缺乏神经系统的拟南芥中鉴定出了离子型谷氨酸受体样基因（GLRs）。随着拟南芥基因组测序项目的完成，一个庞大的GLR基因家族被发现。初步的系统发育分析将拟南芥GLR基因家族分为三个进化枝，并作为最近建立的拟南芥GLR基因家族命名法的基础。我们对iGluR基因家族进行了带有广泛注释的系统发育分析，其中包括所有20个拟南芥GLR基因、大鼠的整个iGluR家族（NR3除外）以及两个原核生物iGluR，即集胞藻GluR0和鱼腥藻GluR。我们的分析支持将拟南芥GLR基因家族分为三个进化枝，并鉴定出在原核生物和真核生物iGluR中均保守以及仅在拟南芥GLR中保守的潜在功能重要氨基酸残基。为了开始研究这三个拟南芥GLR进化枝是否代表不同的功能类别，我们对整个拟南芥GLR基因家族进行了首次全面的mRNA表达分析。基于逆转录聚合酶链反应（RT-PCR），所有拟南芥GLR都是表达基因。这三个拟南芥GLR进化枝并未表现出明显的进化枝特异性器官表达模式。所有20个拟南芥GLR基因都在根中表达。其中，九个进化枝II中的五个基因在8周龄的拟南芥植株中是根特异性表达的。
