BINDING OF THE GRB2 SH2 DOMAIN TO PHOSPHOTYROSINE MOTIFS DOES NOT CHANGE THE AFFINITY OF ITS SH3 DOMAINS FOR SOS PROLINE-RICH MOTIFS
BINDING OF THE GRB2 SH2 DOMAIN TO PHOSPHOTYROSINE MOTIFS DOES NOT CHANGE THE AFFINITY OF ITS SH3 DOMAINS FOR SOS PROLINE-RICH MOTIFS
复制标题
DOI：
10.1002/j.1460-2075.1994.tb06717.x
复制
发表时间：
1994-09-01
期刊：
影响因子：
11.4
通讯作者：
CHARDIN, P
中科院分区：
文献类型：
--
作者：
CUSSAC, D;FRECH, M;CHARDIN, P
与Grb 2结合的磷酸酪氨酸肽诱导Src同源2（SH 2）结构域中的色氨酸荧光变化。亲和力在纳摩尔范围内，She肽具有最高的亲和力，其次是模拟EGF和HGF受体上的Grb 2结合位点的肽，胰岛素和IGF-1受体上的推定位点具有低得多的亲和力。富含脯氨酸的肽与SH 3结构域结合主要在C-末端SH 3中诱导荧光变化。亲和力在微摩尔范围内，最高亲和力的肽模仿Sos C-末端的第一个富含脯氨酸的基序。在该PVPPPVPP基序之前的另外的残基提供对结合的微小贡献，但是在该基序之后的两个残基是重要的并且可能有助于特异性。每个SH 3对每个富含脯氨酸的基序的亲和力太低，不能解释Grb 2-Sos复合物的高稳定性，这表明Grb 2识别Sos C-末端的其他结构特征。磷酸酪氨酸肽与SH 2的结合对SH 3没有影响。因此，Grb 2与受体或酪氨酸磷酸化的相关蛋白质的结合不太可能通过从SH 2传递到SH 3结构域的构象变化来激活Sos的交换因子活性。
Phosphotyrosine peptide binding to Grb2 induces tryptophan fluorescence changes in the Src homology 2 (SH2) domain. Affinities are in the nanomolar range, the She peptide having the highest affinity, followed by peptides mimicking Grb2 binding sites on EGF and HGF receptors, the putative sites on insulin and IGF-1 receptors having much lower affinities. Proline-rich peptide binding to the SH3 domains induces fluorescence changes mainly in the C-terminal SH3. Affinities are in the micromolar range, the highest affinity peptides mimicking the first proline-rich motif of the Sos C-terminus. Additional residues before this PVPPPVPP motif provide a minor contribution to the binding, but the two residues after this motif are important and may contribute to specificity. The affinity of each SH3 for each proline-rich motif is too low to account for the high stability of the Grb2-Sos complex, suggesting that Grb2 recognizes other structural features in the Sos C-terminus. Binding of a phosphotyrosine peptide to the SH2 has no effect on the SH3s. Thus the binding of Grb2 to a receptor or to an associated protein phosphorylated on tyrosines is unlikely to activate the exchange factor activity of Sos through a conformational change transmitted from the SH2 to the SH3 domains.