Galectin-3 is a glycan-binding protein (GBP) that binds β-galactoside glycan structures to orchestrate a variety of important biological events, including the activation of hepatic stellate cells and regulation of immune responses. While the requisite glycan epitopes needed to bind galectin-3 have long been elucidated, the cellular glycoproteins that bear these glycan signatures remain unknown. Given the importance of the three-dimensional (3D) arrangement of glycans in dictating GBP interactions, strategies that allow the identification of GBP receptors in live cells, where the native glycan presentation and glycoprotein expression are preserved, have significant advantages over static and artificial systems. Here we describe the integration of a proximity labeling method and quantitative mass spectrometry to map the glycan and glycoprotein interactors for galectin-3 in live human hepatic stellate cells and peripheral blood mononuclear cells. Understanding the identity of the glycoproteins and defining the structures of the glycans will empower efforts to design and develop selective therapeutics to mitigate galectin-3–mediated biological events.

Galectin-3 是一种聚糖结合蛋白 (GBP)，它结合 β-半乳糖苷聚糖结构以协调各种重要的生物学事件，包括肝星状细胞的激活和免疫反应的调节。虽然结合半乳糖凝集素 3 所需的必需聚糖表位早已被阐明，但具有这些聚糖特征的细胞糖蛋白仍然未知。鉴于聚糖的三维 (3D) 排列在决定 GBP 相互作用中的重要性，允许在保留天然聚糖呈现和糖蛋白表达的活细胞中识别 GBP 受体的策略比静态和人工系统具有显着优势. 在这里，我们描述了邻近标记方法和定量质谱法的整合，以绘制活人肝星状细胞和外周血单核细胞中 galectin-3 的聚糖和糖蛋白相互作用物。了解糖蛋白的特性和定义聚糖的结构将有助于设计和开发选择性疗法以减轻 galectin-3 介导的生物事件。