Van Velzen A G, Da Silva R P, Gordon S, Van Berkel T J
Division of Biopharmaceutics, Leiden-Amsterdam Center for Drug Research, Sylvius Laboratories, The Netherlands.
Biochem J. 1997 Mar 1;322 ( Pt 2)(Pt 2):411-5. doi: 10.1042/bj3220411.
Rat liver Kupffer cell membranes contain a protein that recognizes specifically oxidized low-density lipoproteins (oxLDL). Visualization after blotting under reducing conditions indicates that the receptor is a monomeric protein, with an estimated molecular mass of 115-120 kDa. N-Glycosidase F and endoglycosidase F treatment resulted in a fall in estimated molecular mass of 24 and 11 kDa respectively, whereas O-glycosidase was ineffective. No effect on the extent of interaction with oxLDL was noticed, suggesting that glycans are not essential for ligand recognition. Using a polyclonal antibody to mouse macrosialin, we visualized macrosialin on blot, and compared this glycoprotein with the oxLDL-binding protein. It appears that the two glycoproteins have a similar molecular mass and are comparably affected by treatment with the different glycosidases. Incubation with trypsin resulted in a reduction in the estimated molecular mass of about 25 kDa for both the oxLDL-binding protein and macrosialin. These results indicate that the oxLDL-binding protein and macrosialin are identical, suggesting a role for macrosialin in modified LDL catabolism.
大鼠肝脏库普弗细胞膜含有一种能特异性识别氧化型低密度脂蛋白（oxLDL）的蛋白质。在还原条件下印迹后的可视化结果表明，该受体是一种单体蛋白，估计分子量为115 - 120 kDa。N - 糖苷酶F和内切糖苷酶F处理分别导致估计分子量下降24 kDa和11 kDa，而O - 糖苷酶则无效。未观察到对与oxLDL相互作用程度的影响，这表明聚糖对于配体识别并非必不可少。使用针对小鼠巨唾液酸蛋白的多克隆抗体，我们在印迹上可视化了巨唾液酸蛋白，并将这种糖蛋白与oxLDL结合蛋白进行了比较。似乎这两种糖蛋白具有相似的分子量，并且受到不同糖苷酶处理的影响程度相当。用胰蛋白酶孵育导致oxLDL结合蛋白和巨唾液酸蛋白的估计分子量均降低约25 kDa。这些结果表明，oxLDL结合蛋白和巨唾液酸蛋白是相同的，这表明巨唾液酸蛋白在修饰的LDL分解代谢中起作用。
