Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
Placenta. 2011 Aug;32(8):603-10. doi: 10.1016/j.placenta.2011.05.008. Epub 2011 Jun 12.
In primates and rodents, trophoblast cells synthesize and secrete into the maternal circulation a family of proteins known as pregnancy specific glycoproteins (PSG). The current study was undertaken to characterize the receptor for two members of the murine PSG family, PSG17 and PSG23. Binding of recombinant PSG17 and PSG23 to CHO-K1 and L929 cells and their derived mutants was performed to determine whether these proteins bound to cell surface proteoglycans. We also examined binding of these proteins to cells transfected with syndecans and glypican-1 by flow cytometry. The interaction with glycosaminoglycans was confirmed in solid phase assays. Our results show that PSG17 binds to CD9 and to cell surface proteoglycans while PSG23 binds only to the latter. We found that the amino acids involved in CD9 binding reside in the region of highest divergence between the N1-domains of murine PSGs. For both proteins, the N-terminal domain (designated as N1) is sufficient for binding to cells and the ability to bind cell surface proteoglycans is affected by the cell line employed to generate the recombinant proteins. We conclude that while substantially different at the amino acid level, some murine PSGs share with human PSG1 the ability to bind to cell surface proteoglycans and that at least one PSG binds to more than one type of molecule on the cell surface.
在灵长类动物和啮齿动物中，滋养层细胞合成并分泌到母体循环中的一组蛋白质，称为妊娠特异性糖蛋白（PSG）。本研究旨在表征两种鼠 PSG 家族成员 PSG17 和 PSG23 的受体。通过 CHO-K1 和 L929 细胞及其衍生的突变体进行重组 PSG17 和 PSG23 的结合，以确定这些蛋白是否与细胞表面蛋白聚糖结合。我们还通过流式细胞术检查了这些蛋白与转染了 syndecan 和 glypican-1 的细胞的结合。在固相测定中证实了与糖胺聚糖的相互作用。我们的结果表明，PSG17 结合 CD9 和细胞表面蛋白聚糖，而 PSG23 仅结合后者。我们发现，参与 CD9 结合的氨基酸位于鼠 PSG 的 N1 结构域之间最高差异区域。对于这两种蛋白，N 端结构域（指定为 N1）足以与细胞结合，并且结合细胞表面蛋白聚糖的能力受用于生成重组蛋白的细胞系的影响。我们得出结论，尽管在氨基酸水平上有很大差异，但一些鼠 PSG 与人类 PSG1 具有结合细胞表面蛋白聚糖的能力，并且至少有一种 PSG 与细胞表面上的一种以上类型的分子结合。
