Graham L J, Stoica B A, Shapiro M, DeBell K E, Rellahan B, Laborda J, Bonvini E
Division of Monoclonal Antibodies, US-Food and Drug Administration, Bethesda, Maryland, 20852, USA.
Biochem Biophys Res Commun. 1998 Aug 19;249(2):537-41. doi: 10.1006/bbrc.1998.9177.
SH3 domains are protein modules that interact with proline-rich polypeptide fragments. Cbl is an adapter-like protein known to interact with several SH3 domains, including the PLCgamma1 SH3 domain and the Grb2 amino terminal SH3 domain. Here we explore whether sequences surrounding the PLCgamma1 SH3 domain core sequence (aa.796-851) can affect the binding to Cbl, a target used as a prototypical ligand. Consistent with previous reports, our results demonstrated a weak binding of Cbl to GST fusion proteins that strictly encompass the structural core of the PLCgamma1 SH3 domain but a high-avidity binding to the Grb2 amino-terminal SH3 domain. Inclusion of amino acids immediately flanking the PLCgamma1 SH3 core domain, however, substantially increased binding of Cbl to a level comparable to that of the Grb2 amino-terminal SH3 domain. The interaction of this extended PLCgamma1 SH3 domain fusion protein with Cbl was shown to depend entirely upon the interaction of the domain with a proline-rich motif in Cbl, ruling out the possibility that amino acids adjacent to the core SH3 domain of PLCgamma1 provide independent Cbl binding. These data suggest that sequences surrounding the SH3 domain of PLCgamma1 may contribute to or stabilize the association of the domain with the target protein, thus increasing its binding efficiency.
SH3结构域是与富含脯氨酸的多肽片段相互作用的蛋白质模块。Cbl是一种类似衔接蛋白的蛋白质，已知它能与多个SH3结构域相互作用，包括PLCγ1 SH3结构域和Grb2氨基末端SH3结构域。在这里，我们探究围绕PLCγ1 SH3结构域核心序列（氨基酸796 - 851）的序列是否会影响与Cbl的结合，Cbl是用作典型配体的靶标。与之前的报道一致，我们的结果表明Cbl与严格包含PLCγ1 SH3结构域结构核心的GST融合蛋白的结合较弱，但与Grb2氨基末端SH3结构域有高亲和力结合。然而，包含紧邻PLCγ1 SH3核心结构域的氨基酸会显著增加Cbl的结合，使其达到与Grb2氨基末端SH3结构域相当的水平。这种扩展的PLCγ1 SH3结构域融合蛋白与Cbl的相互作用完全依赖于该结构域与Cbl中富含脯氨酸基序的相互作用，排除了PLCγ1核心SH3结构域相邻氨基酸提供独立Cbl结合的可能性。这些数据表明，围绕PLCγ1 SH3结构域的序列可能有助于或稳定该结构域与靶蛋白的结合，从而提高其结合效率。
