Regulation of the Cool/Pix proteins - Key binding partners of the Cdc42/Rac targets, the p21-activated kinases
Regulation of the Cool/Pix proteins - Key binding partners of the Cdc42/Rac targets, the p21-activated kinases
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DOI：
10.1074/jbc.m107704200
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发表时间：
2002-02-15
影响因子：
4.8
通讯作者：
Yang, WN
中科院分区：
文献类型：
--
作者：
Feng, QY;Albeck, JG;Yang, WN
Cool(文库克隆出来)/Pix(PAR相互作用交换因子)蛋白直接与丝氨酸/苏氨酸激酶PAK家族成员结合并调节其活性。Cool/Pix家族中有三个成员显示出不同的调节活性：(d p50(Cool-1)抑制CDc42/RAC刺激的PAK活性，(Ii)P85(Cool-1)/β-Pix对CDc42/RAC刺激的PAK活性有允许的作用，(Iii)P90(Cool-2)/α-Pix强烈激活PAR。我们最初怀疑这些不同的功能效应是由于在较大的Cool/Pix蛋白的羧基末端发生的结合相互作用，从而使它们能够刺激(或至少允许)而不是抑制PAK活性。这导致了Cat蛋白的鉴定(用于Cool相关的酪氨酸磷酸底物)。然而，在这里，我们发现Cat蛋白与P85(Cool-1)(第523-546位残基)和Cool-2(第647-670位残基)的羧基末端结合，并且Cat与Cool-2的结合实际上不是Cool-2介导的Pay激活所必需的，相反，一个在Cool-1蛋白中存在但在Cool-2中缺失的18个氨基酸区域T1对于Cool-L/β-Pix在体内调控PAK活性是必不可少的。T1的缺失产生了一个模仿Cool-2蛋白的P85(Cool-1)分子，并能够强烈刺激PAR活性。然而，当在Cool-2中加入T1时，Cool-2就失去了直接激活PAK的能力。我们得出结论，T1代表了一个新的调控结构域，它解释了Cool/Pix家族不同成员对PAK活性的特定功能效应。
The Cool (cloned-out of library)/Pix (for PAR-interactive exchange factor) proteins directly bind to members of the PAK family of serine/threonine kinases and regulate their activity. Three members of the Cool/Pix family have shown distinct regulatory activities: (D p50(Cool-1) inhibits Cdc42/Rac-stimulated PAK activity, (ii) p85(Cool-1)/beta-Pix has a permissive effect on Cdc42/Rac-stimulated activity, and (iii) p90(Cool-2)/alpha-Pix strongly activates PAR. We initially suspected that these different functional effects were due to a binding interaction that occurs at the carboxyl-terminal ends of the larger Cool/Pix proteins, thus enabling them to stimulate (or at least permit) rather than inhibit PAK activity. This led to the identification of the Cat proteins (for Cool-associated tyrosine phosphosubstrates). However, here we show that the Cat proteins bind to the carboxyl-terminal ends of p85(Cool-1) (residues 523-546) and Cool-2 (residues 647-670), and that the binding of Cat to Cool-2 in fact is not necessary for the Cool-2-mediated activation of PAY, Rather, an 18-amino acid region, designated T1, that is present in the Cool-1 proteins, but missing in Cool-2, is essential for controlling the regulation of PAK activity by Cool-l/beta-Pix in vivo. Deletion of T1 yielded a p85(Cool-1) molecule that mimicked the Cool-2 protein and was capable of strongly stimulating PAR activity. However, when T1 was added to Cool-2, the ability of Cool-2 to directly activate PAK was lost. We conclude that T1 represents a novel regulatory domain that accounts for the specific functional effects on PAK activity exhibited by the different members of the Cool/Pix family.