A PROTEIN FACTOR FOR RAS P21-DEPENDENT ACTIVATION OF MITOGEN-ACTIVATED PROTEIN (MAP) KINASE THROUGH MAP KINASE KINASE
A PROTEIN FACTOR FOR RAS P21-DEPENDENT ACTIVATION OF MITOGEN-ACTIVATED PROTEIN (MAP) KINASE THROUGH MAP KINASE KINASE
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DOI：
10.1073/pnas.90.3.975
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发表时间：
1993-02-01
影响因子：
11.1
通讯作者：
TAKAI, Y
中科院分区：
文献类型：
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作者：
ITOH, T;KAIBUCHI, K;TAKAI, Y
为了在高等真核生物中确定ras p21的直接靶分子，我们最近建立了ras p21激活丝裂原活化蛋白(MAP)激酶/细胞外信号调节激酶(ERK)的无细胞系统。在这个无细胞体系中，5‘-[γ-硫代]三磷酸结合形式的Ki-ras p21，而不是GDP结合形式，在非洲爪哇卵母细胞胞浆部分存在的情况下，激活内源性非洲爪哇MAPK和重组ERK2。我们用柱层析法从非洲爪哇卵母细胞胞浆组分中分离出两种蛋白因子：一种是MAPK的失活形式，另一种是暂定为ras p21依赖的ERK激动子(REKS)。前者和后者的M(R)值几乎相等，分别为45,000和150,000-200,000，通过凝胶过滤估计。这两个因素都是Ki-ras p21依赖的MAPK/ERK2激活所必需的。这些结果表明，一个额外的蛋白因子(REKS)是Ki-ras p21通过MAP激酶激活MAP激酶所必需的。
To identify the direct target molecule of ras p21 in higher eukaryotes, we have recently developed the cell-free system in which ras p21 activates mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (ERK). In this cell-free system, the guanosine 5'-[gamma-thio]triphosphate-bound form of Ki-ras p21, but not the GDP-bound form, activates endogenous Xenopus MAP kinase as well as recombinant ERK2 in the presence of the cytosol fraction of Xenopus oocytes. We separated two protein factors from the cytosol fraction of Xenopus oocytes by column chromatography: one was the inactive form of MAP kinase kinase and the other was a factor tentatively named ras p21-dependent ERK-kinase stimulator (REKS). The former and latter showed M(r) values of almost-equal-to 45,000 and 150,000-200,000, respectively, as estimated by gel filtration. Both factors were necessary for Ki-ras p21-dependent activation of MAP kinase/ERK2. These results indicate that an additional protein factor (REKS) is essential for Ki-ras p21 to activate MAP kinase through MAP kinase kinase.