Mizoguchi T, Gotoh Y, Nishida E, Yamaguchi-Shinozaki K, Hayashida N, Iwasaki T, Kamada H, Shinozaki K
Laboratory of Plant Molecular Biology, Institute of Physical and Chemical Research (RIKEN), Tsukuba Life Science Center, Tsukuba, Ibaraki, Japan.
Plant J. 1994 Jan;5(1):111-22. doi: 10.1046/j.1365-313x.1994.5010111.x.
Two cDNA clones, cATMPK1 and cATMPK2, encoding MAP kinases (mitogen-activated protein kinases) have been cloned from Arabidopsis thaliana and their nucleotide sequences have been determined. Putative proteins encoded by ATMPK1 and ATMPK2 genes, designated ATMPK1 and ATMPK2, contain 370 and 376 amino acid residues, respectively, and are 88.7% identical at the amino acid sequence level. ATMPK1 and ATMPK2 exhibit significant similarity to rat ERK2 (49%) and Xenopus MAP kinase (50%). The amino acid residues corresponding to the sites of phosphorylation (Thr-Glu-Tyr) that are involved in the activation of MAP kinases are conserved in ATMPK1 and ATMPK2. Northern blot analysis indicates that the ATMPK1 and ATMPK2 mRNAs are significantly present in all the organs except seeds. Genomic Southern blot analysis suggests that there are a few additional genes that are related to ATMPK1 and ATMPK2 in the Arabidopsis genome. Purified Xenopus MAP kinase kinase (MAPK kinase) phosphorylates ATMPK1 and ATMPK2 proteins that have been expressed in Escherichia coli, activating these enzymes. A rapid and transient activation of 46-kDa protein kinase activity that phosphorylated myelin basic protein (MBP) was detected when auxin-starved tobacco BY-2 cells were treated with synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-D). Protein kinase activities which phosphorylated the recombinant ATMPK2 protein also increased rapidly after auxin treatment in the auxin-starved BY-2 cells. These results suggest that auxin may function as an activator of plant MAP kinase homologues, as do various mitogens in animal systems.
已从拟南芥中克隆出两个编码丝裂原活化蛋白激酶（MAP激酶）的cDNA克隆，即cATMPK1和cATMPK2，并测定了它们的核苷酸序列。由ATMPK1和ATMPK2基因编码的推定蛋白，分别命名为ATMPK1和ATMPK2，分别含有370和376个氨基酸残基，在氨基酸序列水平上具有88.7%的同一性。ATMPK1和ATMPK2与大鼠ERK2（49%）和非洲爪蟾MAP激酶（50%）表现出显著的相似性。参与MAP激酶激活的磷酸化位点（苏氨酸-谷氨酸-酪氨酸）对应的氨基酸残基在ATMPK1和ATMPK2中是保守的。Northern印迹分析表明，ATMPK1和ATMPK2 mRNA在除种子以外的所有器官中均大量存在。基因组Southern印迹分析表明，在拟南芥基因组中存在一些与ATMPK1和ATMPK2相关的其他基因。纯化的非洲爪蟾MAP激酶激酶（MAPK激酶）可磷酸化在大肠杆菌中表达的ATMPK1和ATMPK2蛋白，从而激活这些酶。当用合成生长素2,4-二氯苯氧乙酸（2,4-D）处理生长素饥饿的烟草BY-2细胞时，检测到一种快速且短暂的46 kDa蛋白激酶活性的激活，该活性可磷酸化髓鞘碱性蛋白（MBP）。在生长素饥饿的BY-2细胞中，用生长素处理后，磷酸化重组ATMPK2蛋白的蛋白激酶活性也迅速增加。这些结果表明，生长素可能作为植物MAP激酶同源物的激活剂发挥作用，就像动物系统中的各种有丝分裂原一样。
