Identification of two SH3-binding motifs in the regulatory subunit of phosphatidylinositol 3-kinase.
Identification of two SH3-binding motifs in the regulatory subunit of phosphatidylinositol 3-kinase.
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DOI：
10.1016/s0021-9258(17)42115-6
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发表时间：
1994-01
期刊：
影响因子：
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通讯作者：
R. Kapeller;K. Prasad;Ottmar Janssen;W. Hou;Brian Schaffhausen;Christopher E. Rudd;L. Cantley
中科院分区：
文献类型：
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作者：
R. Kapeller;K. Prasad;Ottmar Janssen;W. Hou;Brian Schaffhausen;Christopher E. Rudd;L. Cantley
SRC同源3(SH3)结构域最近被证明与3BP1、3BP2和SOS中包含的富含脯氨酸的序列结合。在最近的一项研究中，我们证明了磷脂酰肌醇3-激酶(PI-3-Kinase)与Fyn SH3结构域有关。在这里，我们证明了P85，PI 3-激酶的调节亚单位，直接与Ab1，Lck，Fyn和P85本身的SH3结构域结合。对P85氨基酸序列的分析发现，其N-末端有两个富含Pro的序列，与3BP1、3BP2和SOS中的序列相似。为了测试这些序列是否介导了P85与SH3结构域的结合，我们合成了两个氨基酸组成与P85α富含脯氨酸序列相对应的多肽，并用于竞争分析。两种多肽在抑制PI3K活性和P85α与Fyn SH3结构域的结合方面同样有效，而对照多肽则没有作用。这些结果表明，与在3BP1和SOS中一样，P85中富含脯氨酸的序列介导了它与SH3结构域的相互作用。这些结果还表明，P85的SH3结构域可能与同一亚基的富含Pro的基序“自关联”，这是PI-3-K调节机制的一部分。
Src homology 3 (SH3) domains have been recently shown to bind to proline-rich sequences contained in 3BP1, 3BP2, and SOS. In a recent study we demonstrated that phosphatidylinositol 3-kinase (PI 3-kinase) associates with the Fyn SH3 domain. Here we show that p85, the regulatory subunit of PI 3-kinase, binds directly to the SH3 domains of Abl, Lck, Fyn, and p85 itself. An examination of p85 amino acid sequence revealed two proline-rich sequences in its N-terminal region similar to those present in 3BP1, 3BP2, and SOS. To test whether these sequences mediate the association of p85 with SH3 domains two peptides with amino acid composition corresponding to the p85 alpha proline-rich sequences were synthesized and used in competition assays. Both peptides worked equally well in inhibiting the binding of PI 3-kinase activity and p85 alpha to Fyn SH3 domain, whereas a control peptide had no effect. These results indicate that, as in 3BP1 and SOS, the proline-rich sequences in p85 mediate its interaction with SH3 domains. These results also suggest that the SH3 domain of p85 may “self-associate” with the proline-rich motifs of the same subunit as part of the PI 3-kinase regulatory mechanism.