Attempt for regulating biologial activities by use of molecular recognition of SH2 and SH3 domains.

我们发现了一个接头蛋白Ash/Grb2，它将酪氨酸激酶信号传递到下游，导致Ras的激活。这种蛋白有一个SH2和两个SH3结构域。在本项目中，我们试图澄清Ash/Grb2 SH3结构域的结合蛋白，然后从牛脑中纯化SH3结合蛋白。其中，150 kDa和65 kDa蛋白为新蛋白。对这些蛋白进行cDNA克隆后，发现150 kDa蛋白是突触蛋白同工酶之一。另一方面，发现65 kDa蛋白与Wiskott-Aldrich综合征蛋白（WASP）同源。因此我们将其命名为N-WASP。N-WASP具有PH结构域、GBD/CRIB基序、IQ基序、类脯氨酸基序、类cofilin基序和富含脯氨酸的序列。它结合到Ash/Grb2 SH3结构域，在酪氨酸激酶的下游被激活。活化的N-WASP以依赖Cdc42的方式聚合肌动蛋白丝，导致丝状足形成。

We found an adaptor protein, Ash/Grb2 which transmits tyrosine kinase signals to downstream, resulting in activation of Ras. This protein has one SH2 and two SH3 domains. In this project, we attempted to clarify binding proteins to Ash/Grb2 SH3 domain, and then purified SH3-binding proteins from bovine brain. Among them, two proteins (150 kDa and 65 kDa proteins) were new. After cDNA clonings of these proteins, 150 kDa protein was found to be one of synaptojamin isozymes. On the other hand, 65 kDa protein was found to be homologous to Wiskott-Aldrich syndrome protein (WASP). We therefore named it N-WASP.N-WASP has a PH domain, GBD/CRIB motif, IQ motif, verprolin-like motif, cofilin-like motif and proline-rich sequences. It binds to Ash/Grb2 SH3 domain and is activated downstream of tyrosine kinases. Activated N-WASP polymerizes actin filament in Cdc42 dependent manner, resulting in filopodia formation.