Zhou Hong-Wei, Nussbaumer Cindy, Chao Yvonne, DeLong Alison
Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island 02912, USA.
Plant Cell. 2004 Mar;16(3):709-22. doi: 10.1105/tpc.018994. Epub 2004 Feb 18.
The heterotrimeric protein phosphatase 2A (PP2A) complex comprises a catalytic subunit and regulatory A and B subunits that modulate enzyme activity and mediate interactions with other proteins. We report here the results of a systematic analysis of the Arabidopsis (Arabidopsis thaliana) regulatory A subunit gene family, which includes the ROOTS CURL IN NAPHTHYLPHTHALAMIC ACID1 (RCN1), PP2AA2, and PP2AA3 genes. All three A subunit isoforms accumulate in the organs of seedlings and adult plants, suggesting extensive overlap in expression domains. We have isolated pp2aa2 and pp2aa3 mutants and found that their phenotypes are largely normal and do not resemble that of rcn1. Whereas rcn1 pp2aa2 and rcn1 pp2aa3 double mutants exhibit striking abnormalities in all stages of development, the pp2aa2 pp2aa3 double mutant shows only modest defects. Together, these data suggest that RCN1 performs a cardinal role in regulation of phosphatase activity and that PP2AA2 and PP2AA3 functions are unmasked only when RCN1 is absent.
异源三聚体蛋白磷酸酶2A（PP2A）复合物由一个催化亚基以及调节性A亚基和B亚基组成，这些亚基可调节酶活性并介导与其他蛋白质的相互作用。我们在此报告对拟南芥调节性A亚基基因家族的系统分析结果，该家族包括根卷曲萘基邻苯二甲酸1（RCN1）、PP2AA2和PP2AA3基因。所有三种A亚基异构体均在幼苗和成年植物的器官中积累，表明表达域存在广泛重叠。我们分离出了pp2aa2和pp2aa3突变体，发现它们的表型基本正常，与rcn1不同。虽然rcn1 pp2aa2和rcn1 pp2aa3双突变体在发育的各个阶段均表现出明显异常，但pp2aa2 pp2aa3双突变体仅表现出适度缺陷。这些数据共同表明，RCN1在磷酸酶活性调节中起主要作用，并且只有在RCN1缺失时，PP2AA2和PP2AA3的功能才会显现出来。
