巨噬细胞新型氧化低密度脂蛋白结合蛋白的研究

小鼠腹腔巨噬细胞（ＭＰＭ）膜上存在能结合氧化低密度脂蛋白（ｏｘ－ＬＤＬ）的Ａ类清道夫受体（ＳＲ－Ａ），但用配体印迹技术研究制备ＭＰＭ膜蛋白，发现还存在一种新型ｏｘ－ＬＤＬ膜结合蛋白，其分子量低于ＳＲ－Ａ，为９２ｋＤ它不结合乙酰化低密度脂蛋白ａｃ－ＬＤＬ），与配体的结合也不受还原剂的影响，但唾液酸酶处理则明显减弱其与ｏｘ－ＬＤＬ的结合，未标记ｏｘ－ＬＤＬ能竞争性抑制（＾１２５Ｉ）ｏｘ－ＬＤＬ与９２ｋ

A Novel Oxidized Low Density Lipoprotein binding Protein in Macrophage

Scavenger receptor A(SR A)on the mouse peritoneal macrophages(MPM) mediates the endocytic uptake of oxidized low density lipoproteins(ox LDL). However, using ligand blotting and immunoblotting, a novel macrophage membrane protein binding to ox LDL with estimated molecular mass of 92 kD was found. This membrane protein could not bind to ac LDL. Its binding to ligands was not affected by reducing reagents either. Preincubation with medium containing neuraminidase dramatically decreased binding of the 92 kD membrane protein to ox LDL. Excess amounts of ox LDL could completely block the binding of 125 I] ox LDL to 92 kD membrane protein, but polyI, dextran sulfate and fucoidin showed partial competitive inhibition effects to the binding. These results suggest that the novel 92 kD membrane protein plays important role in the MPM uptake of ox LDL.