Kolb-Bachofen V
Abteilung für Immunobiologie, Heinrich-Heine-Universität Düsseldorf, BRD.
Pathobiology. 1991;59(4):272-5. doi: 10.1159/000163661.
Rat liver macrophages express a galactose-specific receptor which mediates endocytosis of particles or neuraminidase-treated blood cells. From rat serum we now have isolated a galactose-specific lectin by affinity chromatography. Comparative analysis of this serum galactose-binding protein with the galactose-specific particle receptor protein purified from rat liver macrophages and with the acute-phase protein C-reactive protein (CRP) revealed a close relation or identity of these proteins. An apparent molecular weight of 30 kilodaltons was determined for all three proteins by SDS-PAGE under reducing conditions and of about 130 kilodaltons by native PAGE. All three proteins exhibit the same pentameric, ring-shaped structure. Antibodies raised against the serum galactose-binding protein or against the macrophage receptor did cross-react. Monoclonal antibodies raised against rat CRP labeled liver macrophage but not hepatocyte surfaces and reacted with all three isolated proteins in a Western blot assay. Furthermore, the galactose-specific particle receptor could be functionally replaced by purified CRP. Northern blot analysis showed that the CRP is not synthesized in the macrophages but appears to be acquired from hepatocytes or blood. We now conclude that a membrane-bound form of CRP functions as the recycling galactose-specific particle receptor in rat liver Kupffer cells.
大鼠肝脏巨噬细胞表达一种半乳糖特异性受体，该受体介导颗粒或经神经氨酸酶处理的血细胞的内吞作用。我们现在通过亲和层析从大鼠血清中分离出了一种半乳糖特异性凝集素。对这种血清半乳糖结合蛋白与从大鼠肝脏巨噬细胞中纯化的半乳糖特异性颗粒受体蛋白以及急性期蛋白C反应蛋白（CRP）进行比较分析，发现这些蛋白之间存在密切关系或相同性。在还原条件下通过SDS-PAGE测定这三种蛋白的表观分子量均为30千道尔顿，通过非变性PAGE测定约为130千道尔顿。这三种蛋白均呈现相同的五聚体环状结构。针对血清半乳糖结合蛋白或巨噬细胞受体产生的抗体确实会发生交叉反应。针对大鼠CRP产生的单克隆抗体标记肝脏巨噬细胞表面但不标记肝细胞表面，并且在蛋白质免疫印迹分析中与所有三种分离的蛋白发生反应。此外，纯化的CRP在功能上可以替代半乳糖特异性颗粒受体。Northern印迹分析表明，CRP不在巨噬细胞中合成，而是似乎从肝细胞或血液中获得。我们现在得出结论，CRP的一种膜结合形式在大鼠肝脏枯否细胞中作为循环利用的半乳糖特异性颗粒受体发挥作用。
