Mitchel Y B, Rifici V A, Eder H A
Biochim Biophys Acta. 1987 Feb 14;917(2):324-32. doi: 10.1016/0005-2760(87)90137-8.
We have used a preparation of rat liver plasma membranes to study the binding of rat apolipoprotein E-deficient HDL to rat liver. The membranes were found to bind HDL by a saturable process that was competed for by excess unlabeled HDL. The binding was temperature-dependent and was 85% receptor-mediated when incubated at 4, 22 and 37 degrees C. The affinity of the binding site for the HDL was consistent at all temperatures, while the maximum binding capacity increased at higher temperatures. The specific binding of HDL to the membranes did not require calcium and was independent of the concentration of NaCl in the media. The effect of varying the pH of the media on HDL binding was small, being 30% higher at pH 6.5 than at pH 9.0. Both rat HDL and human HDL3 were found to compete for the binding of rat HDL to the membranes, whereas rat VLDL remnants and human LDL did not compete. At 4 degrees C, complexes of dimyristoylphosphatidylcholine (DMPC) and apolipoproteins A-I, A-IV and the C apolipoproteins, but not apolipoprotein E, competed for HDL binding to the membranes. At 22 and 37 degrees C, all DMPC-apolipoprotein complexes competed to a similar extent, DMPC vesicles that contained no protein did not compete for the binding of HDL. These results suggest that the rat liver possesses a specific receptor for apolipoprotein E-deficient HDL that recognizes apolipoproteins A-I, A-IV and the C apolipoproteins as ligands.
我们使用大鼠肝细胞膜制剂来研究大鼠载脂蛋白E缺乏的高密度脂蛋白（HDL）与大鼠肝脏的结合。发现这些膜通过一个可饱和的过程结合HDL，该过程可被过量的未标记HDL竞争。这种结合是温度依赖性的，在4℃、22℃和37℃孵育时，85%是由受体介导的。结合位点对HDL的亲和力在所有温度下都是一致的，而最大结合能力在较高温度下增加。HDL与膜的特异性结合不需要钙，并且与培养基中NaCl的浓度无关。改变培养基pH对HDL结合的影响很小，在pH 6.5时比在pH 9.0时高30%。发现大鼠HDL和人HDL3都能竞争大鼠HDL与膜的结合，而大鼠极低密度脂蛋白（VLDL）残粒和人低密度脂蛋白（LDL）则不能竞争。在4℃时，二肉豆蔻酰磷脂酰胆碱（DMPC）与载脂蛋白A-I、A-IV和C族载脂蛋白形成的复合物，但不包括载脂蛋白E，能竞争HDL与膜的结合。在22℃和37℃时，所有DMPC-载脂蛋白复合物的竞争程度相似，不含蛋白质的DMPC囊泡不能竞争HDL的结合。这些结果表明，大鼠肝脏拥有一种针对载脂蛋白E缺乏的HDL的特异性受体，该受体将载脂蛋白A-I、A-IV和C族载脂蛋白识别为配体。
