Abstract

Pregnancy-specific beta 1 glycoprotein (PSG1) is secreted from trophoblast cells of the human placenta in increasing concentrations as pregnancy progresses, becoming one of the most abundant proteins in maternal serum in the third trimester. PSG1 has seven potential N-linked glycosylation sites across its four domains. We carried out glycomic and glycoproteomic studies to characterize the glycan composition of PSG1 purified from serum of pregnant women and identified the presence of complex N-glycans containing poly LacNAc epitopes with α2,3 sialyation at four sites. Using different techniques, we explored whether PSG1 can bind to galectin-1 (Gal-1) as these two proteins were previously shown to participate in processes required for a successful pregnancy. We confirmed that PSG1 binds to Gal-1 in a carbohydrate-dependent manner with an affinity of the interaction of 0.13 μM. In addition, we determined that out of the three N-glycosylation-carrying domains, only the N and A2 domains of recombinant PSG1 interact with Gal-1. Lastly, we observed that the interaction between PSG1 and Gal-1 protects this lectin from oxidative inactivation and that PSG1 competes the ability of Gal-1 to bind to some but not all of its glycoprotein ligands.

中文翻译：

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妊娠特异性糖蛋白 1 的聚糖表征及其作为新型 Galectin-1 配体的鉴定。

摘要

妊娠特异性 β 1 糖蛋白 (PSG1) 从人类胎盘的滋养层细胞分泌，随着妊娠的进行，浓度逐渐增加，成为妊娠晚期母体血清中含量最丰富的蛋白质之一。PSG1 在其四个结构域中具有七个潜在的 N 联糖基化位点。我们进行了糖组学和糖蛋白组学研究，以表征从孕妇血清中纯化的 PSG1 的聚糖组成，并确定了复杂 N-聚糖的存在，其中包含在四个位点具有 α2,3 唾液酸化的聚 LacNAc 表位。我们使用不同的技术探索了 PSG1 是否可以与 galectin-1 (Gal-1) 结合，因为这两种蛋白质之前已被证明参与成功怀孕所需的过程。我们证实 PSG1 以碳水化合物依赖的方式与 Gal-1 结合，相互作用的亲和力为 0.13 μM。此外，我们确定在三个 N-糖基化携带域中，只有重组 PSG1 的 N 和 A2 域与 Gal-1 相互作用。最后，我们观察到 PSG1 和 Gal-1 之间的相互作用保护这种凝集素免于氧化失活，并且 PSG1 与 Gal-1 竞争结合其部分但不是全部糖蛋白配体的能力。