BCR-ABL drives chronic myeloid leukemia (CML). BCR binding to GRB2 transduces signaling via the Ras/MAPK pathway. Despite considerable data confirming the binding, molecular-level understanding of exactly how the two proteins interact, and, especially, what are the determinants of the specificity of the SH2^GRB2 domain-phosphorylated BCR (pBCR) recognition are still open questions. Yet, this is vastly important for understanding binding selectivity, and for predicting the phosphorylated receptors, or peptides, that are likely to bind. Here, we uncover these determinants and ascertain to what extent they relate to the affinity of the interaction. Toward this end, we modeled the complexes of the pBCR and SH2^GRB2 and other pY/Y-peptide-SH2 complexes and compared their specificity and affinity. We observed that pBCR’s ₁₇₆FpYVNV₁₈₀ motif is favorable and specific to SH2^GRB2, similar to pEGFR, but not other complexes. SH2^GRB2 contains two binding pockets: pY-binding recognition pocket triggers binding, and the specificity pocket whose interaction is governed by N179 in pBCR and W121 in SH2^GRB2. Our proposed motif with optimal affinity to SH2^GRB2 is E/D-pY-E/V-N-I/L. Collectively, we provide the structural basis of BCR-ABL recruitment of GRB2, outline its specificity hallmarks, and delineate a blueprint for prediction of BCR-binding scaffolds and for therapeutic peptide design.

BCR-ABL 导致慢性粒细胞白血病 (CML)。BCR 与 GRB2 结合通过 Ras/MAPK 途径转导信号传导。尽管有大量数据证实了这种结合，但对两种蛋白质如何相互作用的分子水平理解，尤其是 SH2 GRB2 结构域^磷酸化 BCR (pBCR) 识别的特异性的决定因素是什么，仍然是悬而未决的问题。然而，这对于理解结合选择性以及预测可能结合的磷酸化受体或肽非常重要。在这里，我们揭示了这些决定因素，并确定它们与相互作用的亲和力有多大关系。为此，我们对 pBCR 和 SH2 ^{GRB2的复合物进行了建模}和其他 pY/Y-肽-SH2 复合物并比较了它们的特异性和亲和力。我们观察到 pBCR 的₁₇₆ FpYVNV _{180基序对 SH2} ^GRB2有利且具有特异性，与 pEGFR 类似，但与其他复合物不同。SH2 ^GRB2包含两个结合口袋：pY 结合识别口袋触发结合，特异性口袋的相互作用由 pBCR 中的 N179 和 SH2 ^GRB2中的 W121 控制。我们提出的与 SH2 ^GRB2具有最佳亲和力的基序是 E/D-pY-E/VNI/L。总的来说，我们提供了 BCR-ABL 招募 GRB2 的结构基础，概述了其特异性标志，并描绘了预测 BCR 结合支架和治疗性肽设计的蓝图。