Nagano Y, Murai N, Matsuno R, Sasaki Y
Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Japan.
Plant Cell Physiol. 1993 Apr;34(3):447-55.
Eleven cDNA clones (pra1 to pra9A, pra9B, and pra9C) were isolated from a pea (Pisum sativum) leaf cDNA library which were similar to small GTP-binding proteins. These cDNAs encoded proteins of 22-25 kDa, which exhibited 45-92% identity to one another at the amino acid level. The putative proteins included the characteristic sequences of ras-related small GTP-binding proteins: four conserved domains involved in binding of GTP/GDP; an effector domain; and cysteine residues at the COOH-terminus. Indeed, the pra6 protein, expressed in Escherichia coli, clearly showed GTP-binding activity. Phylogenetic analysis showed that these clones can be classified into two subgroups: proteins encoded by pra1 to pra7 being related to ypt3 and rab11 proteins; and proteins encoded by pra8, pra9A, pra9B, and pra9C being related to YPT1 and rab1 proteins. The effector sequences in these two subgroups were different. RNA gel blot analysis showed that most of the corresponding genes are differentially expressed in pea leaves and roots. Variations in expression were also observed for structurally related genes.
从豌豆（Pisum sativum）叶cDNA文库中分离出11个cDNA克隆（pra1至pra9A、pra9B和pra9C），它们与小GTP结合蛋白相似。这些cDNA编码22 - 25 kDa的蛋白质，在氨基酸水平上彼此具有45 - 92%的同一性。推定的蛋白质包括ras相关小GTP结合蛋白的特征序列：参与GTP/GDP结合的四个保守结构域；一个效应结构域；以及COOH末端的半胱氨酸残基。实际上，在大肠杆菌中表达的pra6蛋白明显显示出GTP结合活性。系统发育分析表明，这些克隆可分为两个亚组：pra1至pra7编码的蛋白质与ypt3和rab11蛋白相关；pra8、pra9A、pra9B和pra9C编码的蛋白质与YPT1和rab1蛋白相关。这两个亚组中的效应序列不同。RNA凝胶印迹分析表明，大多数相应基因在豌豆叶和根中差异表达。在结构相关基因中也观察到表达的变化。
