ASCT2 (SLC1A5) is a sodium-dependent neutral amino acid transporter that controls amino acid homeostasis in peripheral tissues. ASCT2 is upregulated in cancer, where it modulates intracellular glutamine levels, fueling cell proliferation. Nutrient deprivation via ASCT2 inhibition provides an emerging strategy for cancer therapy. Here, guided by a homology model of ASCT2 in an outward-facing conformation, we rationally designed novel inhibitors exploiting stereospecific pockets in the substrate binding site. A cryo-EM structure of ASCT2 in complex with inhibitor (Lc-BPE) validated our predictions and was subsequently refined based on computational analysis. The final structures, combined with MD simulations, show that the inhibitor samples multiple conformations in the ASCT2 binding site. Our results demonstrate the utility of combining computational modeling and cryo-EM for SLC ligand discovery, and a viable strategy for structure determination of druggable conformational states for challenging membrane protein targets.

中文翻译：

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合理设计抑制ASCT2的立体结构基础

ASCT2（SLC1A5）是钠依赖性的中性氨基酸转运蛋白，它控制周围组织中的氨基酸稳态。ASCT2在癌症中上调，它调节细胞内谷氨酰胺水平，促进细胞增殖。通过抑制ASCT2的营养剥夺为癌症治疗提供了一种新兴策略。在这里，由面向外构象的ASCT2同源模型指导，我们合理设计了利用底物结合位点的立体特异性口袋的新型抑制剂。ASCT2与抑制剂（Lc-BPE）配合使用的低温EM结构验证了我们的预测，随后根据计算分析对其进行了完善。最终结构与MD模拟相结合，表明该抑制剂在ASCT2结合位点取样了多个构象。