Tiemeyer M, Brandley B K, Ishihara M, Swiedler S J, Greene J, Hoyle G W, Hill R L
Glycomed Incorporated, Alameda, California 94501.
J Biol Chem. 1992 Jun 15;267(17):12252-7.
A receptor uniquely found on the surface of rat Kupffer cells was shown previously to bind oligosaccharides terminating in galactose, N-acetylgalactosamine, and fucose. To analyze further the binding specificity of the receptor, receptor-mediated adhesion of transfected COS cells to immobilized glycolipids of known structure was measured. The glycolipid Gb4Cer (GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1Cer) was the best ligand. Gb5Cer (GalNAc alpha 1-3GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1Cer) and LacCer (Gal beta 1-4Glc beta 1Cer) bound more weakly (five times less than Gb4Cer) and Gb3Cer (Gal alpha 1-4Gal beta 1-4Glc beta 1Cer), and g3Cer(GalNAc beta 1-4Gal beta 1-4Glc beta 1Cer) bound even more weakly (60 times less than Gb4Cer). Gangliosides did not support adhesion of transfected cells. The adhesion of COS cells transfected with plasmids encoding variants of the receptor was also examined. In each variant, either tryptophan 498 or 523, which are conserved in most C-type lectins, was replaced by one of several amino acids. Variants that retained binding activity had the same specificity as the normal receptor. Differences between variants were noted, however, in maximal levels of adhesion and these differences correlated with altered expression of the receptor variants in COS cells.
先前已表明，一种仅在大鼠库普弗细胞表面发现的受体能够结合以半乳糖、N-乙酰半乳糖胺和岩藻糖结尾的寡糖。为了进一步分析该受体的结合特异性，我们检测了转染的COS细胞通过受体介导与固定化的已知结构糖脂的黏附情况。糖脂Gb4Cer（GalNAcβ1-3Galα1-4Galβ1-4Glcβ1Cer）是最佳配体。Gb5Cer（GalNAcα1-3GalNAcβ1-3Galα1-4Galβ1-4Glcβ1Cer）和LacCer（Galβ1-4Glcβ1Cer）的结合较弱（比Gb4Cer少五倍），而Gb3Cer（Galα1-4Galβ1-4Glcβ1Cer）和g3Cer（GalNAcβ1-4Galβ1-4Glcβ1Cer）的结合更弱（比Gb4Cer少60倍）。神经节苷脂不支持转染细胞的黏附。我们还检测了用编码该受体变体的质粒转染的COS细胞的黏附情况。在每个变体中，大多数C型凝集素中保守的色氨酸498或523被几种氨基酸之一取代。保留结合活性的变体具有与正常受体相同的特异性。然而，在最大黏附水平上注意到了变体之间的差异，并且这些差异与COS细胞中受体变体表达的改变相关。
