Casamayor A, Pérez-Callejón E, Pujol G, Ariño J, Ferrer A
Department de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Plant Mol Biol. 1994 Oct;26(1):523-8. doi: 10.1007/BF00039564.
We have recently reported the existence of multiple isoforms of the catalytic subunit of protein phosphatase 2A (PP2A) in Arabidopsis thaliana and the molecular cloning of cDNAs encoding three of these proteins (PP2A-1, PP2A-2, PP2A-3). The reported cDNA encoding PP2A-3 was truncated at the 5' terminus, lacking a short fragment of the N-terminal coding sequence. We have now isolated a near full-length cDNA encoding the entire PP2A-3 protein (313 residues). The clone includes 188 nucleotides of 5'-untranslated region, where a 44 bp long poly(GA) track is found. We also describe the cloning of a cDNA encoding a fourth isoform of PP2A (PP2A-4). The polypeptide contains 313 residues being 98% identical to PP2A-3 and only 80% identical to both PP2A-1 and PP2A-2. The mRNA for PP2A-4 is 1.4 kb in length and, although predominantly expressed in roots, it is also found in other organs. It is concluded that in A. thaliana the isoforms of PP2A can be grouped in two extremely conserved subfamilies.
我们最近报道了拟南芥中蛋白质磷酸酶2A（PP2A）催化亚基存在多种同工型，并对编码其中三种蛋白质（PP2A-1、PP2A-2、PP2A-3）的cDNA进行了分子克隆。报道的编码PP2A-3的cDNA在5'末端被截断，缺少N端编码序列的一小段片段。我们现在分离出了一个编码完整PP2A-3蛋白（313个氨基酸残基）的近全长cDNA。该克隆包含188个核苷酸的5'非翻译区，其中发现了一个44bp长的聚（GA）序列。我们还描述了编码PP2A第四种同工型（PP2A-4）的cDNA的克隆。该多肽包含313个氨基酸残基，与PP2A-3的同源性为98%，与PP2A-1和PP2A-2的同源性仅为80%。PP2A-4的mRNA长度为1.4kb，虽然主要在根中表达，但在其他器官中也有发现。得出的结论是，在拟南芥中，PP2A的同工型可以分为两个极其保守的亚家族。
