RhoA binds to the amino terminus of MEKK1 and regulates its kinase activity
RhoA binds to the amino terminus of MEKK1 and regulates its kinase activity
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DOI：
10.1074/jbc.m309525200
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发表时间：
2004-01-16
影响因子：
4.8
通讯作者：
Cobb, MH
中科院分区：
文献类型：
--
作者：
Gallagher, ED;Gutowski, S;Cobb, MH
MEKK1 是一种丝裂原激活的蛋白激酶激酶 (MAP3K)，可以调节 c-Jun 氨基末端激酶 (JNK) MAP 激酶级联。 MEKK1 由激酶结构域和长氨基末端调节结构域组成。该氨基末端结构域具有支架功能，可以组装 JNK 和 ERK MAP 激酶级联的模块。最近，我们证明MEKK1与p115 Rho GTP酶激活蛋白结合，p115 Rho GTP酶激活蛋白对RhoA具有GTP酶激活蛋白活性。因此，我们测试了 Rho GTPases 是否与 MEKK1 的调节域相互作用。 RhoA（而不是 Rac 或 Cdc42）与 MEKK1 氨基末端三分之一的位点结合，其中包括其 PHD 结构域。 MEKK1 PHD 结构域中必需的半胱氨酸的突变可阻止这种相互作用。 Rho-GTP 可将全长 MEKK1 的激酶活性刺激至 MEK4 的 10 倍，但在导致 ERK2 修饰的条件下，MEKK1 似乎不会泛素化。总之，我们描述了 Rho GTPases 影响 MEKK1 调节和功能的新点。
MEKK1 is a mitogen-activated protein kinase kinase kinase (MAP3K) that can regulate the c-Jun amino-terminal kinase (JNK) MAP kinase cascade. MEKK1 is comprised of a kinase domain and a long amino-terminal regulatory domain. This amino-terminal domain has a scaffold function in that it can assemble modules of the JNK and ERK MAP kinase cascades. Recently, we have demonstrated that MEKK1 binds to p115 Rho GTPase-activating protein, which has GTPase-activating protein activity toward RhoA. Thus, we tested whether Rho GTPases interact with the regulatory domain of MEKK1. RhoA, but not Rac or Cdc42, binds to a site in the amino-terminal one-third of MEKK1, which includes its PHD domain. The interaction is prevented by mutation of the essential cysteine in the MEKK1 PHD domain. Rho-GTP stimulates the kinase activity of full-length MEKK1 as much as 10-fold toward MEK4 but does not appear to be ubiquitinated by MEKK1 under conditions that result in modification of ERK2. In summary, we have characterized a novel point at which Rho GTPases impinge upon the regulation and function of MEKK1.