The Ras-RAF-MEK-ERK signaling axis, commonly mutated in human cancers, is highly regulated to prevent aberrant signaling in healthy cells. One of the pathway modulators, 14–3–3, a constitutive dimer, induces RAF dimerization and activation by binding to a phosphorylated motif C-terminal to the RAF kinase domain. Recent work has suggested that a C-terminal “DTS” region in BRAF is necessary for this 14–3–3-mediated activation. We show that the catalytic activity and ATP binding affinity of the BRAF:14–3–3 complex is insensitive to the presence or absence of the DTS, while the ATP sites of both BRAF molecules are identical and available for binding. We also present a crystal structure of the apo BRAF:14–3–3 complex showing that the DTS is not required to attain the catalytically active conformation of BRAF. Rather, BRAF dimerization induced by 14–3–3 is the key step in activation, allowing the active BRAF:14–3–3 tetramer to achieve catalytic activity comparable to the constitutively active oncogenic BRAF V600E mutant.

中文翻译：

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C末端14–3–3结合诱导的二聚化足以实现BRAF激酶激活。

通常在人类癌症中发生突变的Ras-RAF-MEK-ERK信号转导轴受到高度调节，以防止健康细胞中的异常信号转导。其中一种途径调节剂14–3–3是组成型二聚体，通过与RAF激酶结构域C端的磷酸化基序结合，诱导RAF二聚化和激活。最近的工作表明，BRAF的C端“ DTS”区域对于14–3–3介导的激活是必要的。我们显示，BRAF：14-3-3配合物的催化活性和ATP结合亲和力对DTS的存在或不敏感，而两个BRAF分子的ATP位点相同且可结合。我们还介绍了apo BRAF：14-3-3复合物的晶体结构，表明不需要DTS即可获得BRAF的催化活性构象。而是