PI 3-KINASE - STRUCTURAL AND FUNCTIONAL-ANALYSIS OF INTERSUBUNIT INTERACTIONS
PI 3-KINASE - STRUCTURAL AND FUNCTIONAL-ANALYSIS OF INTERSUBUNIT INTERACTIONS
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DOI：
10.1002/j.1460-2075.1994.tb06289.x
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发表时间：
1994-02-01
期刊：
影响因子：
11.4
通讯作者：
WATERFIELD, MD
中科院分区：
文献类型：
--
作者：
DHAND, R;HARA, K;WATERFIELD, MD
磷脂酰肌醇（PI） 3-激酶具有一个85 kDa的亚基（p85 α），通过SH2结构域介导其与活化的蛋白酪氨酸激酶受体的关联，以及一个110 kDa的亚基（p110），具有内在的催化活性。在体内和体外，p85 α和相关蛋白p85 β与重组p110形成稳定的复合物。利用p85 sh2区谷胱甘肽s -转移酶（GST）融合蛋白，发现104个氨基酸直接结合p110蛋白，而该区域的缺失突变体进一步将结合位点定义为35个氨基酸序列。突变体p85alpha蛋白在小鼠L细胞中的瞬时表达表明，它在体内不能结合PI 3-激酶活性。p110蛋白上相互作用互补位点的定位确定了p110 n端区域88个氨基酸，这些氨基酸介导了该亚基与p85 α或p85 β蛋白的结合。预测p85的sh2间区是由两个长反平行α螺旋组成的卷曲线圈的独立折叠模块。p85的预测结构表明了亚基间相互作用的基础，并讨论了这种相互作用与PI 3-激酶复合物调节的相关性。
Phosphatidylinositol (PI) 3-kinase has an 85 kDa subunit (p85alpha) which mediates its association with activated protein tyrosine kinase receptors through SH2 domains, and an 110 kDa subunit (p110) which has intrinsic catalytic activity. Here p85alpha and a related protein p85beta are shown to form stable complexes with recombinant p110 in vivo and in vitro. Using a panel of glutathione S-transferase (GST) fusion proteins of the inter-SH2 region of p85, 104 amino acids were found to bind directly the p110 protein, while deletion mutants within this region further defined the binding site to a sequence of 35 amino acids. Transient expression of the mutant p85alpha protein in mouse L cells showed it was unable to bind PI 3-kinase activity in vivo. Mapping of the complementary site of interaction on the p110 protein defined 88 amino acids in the N-terminal region of p110 which mediate the binding of this subunit to either the p85alpha or the p85beta proteins. The inter-SH2 region of p85 is predicted to be an independently folded module of a coiled-coil of two long anti-parallel alpha-helices. The predicted structure of p85 suggests a basis for the intersubunit interaction and the relevance of this interaction with respect to the regulation of the PI 3-kinase complex is discussed.