Ghiselli G, Crump W L, Gotto A M
Biochem Biophys Res Commun. 1986 Aug 29;139(1):122-8. doi: 10.1016/s0006-291x(86)80088-2.
Rat apoA-IV complexes with dimyristoyl phosphatidylcholine (apoA-IV-DMPC) have been prepared and their ability to bind to purified rat liver plasma membranes investigated. Binding equilibrium at 37 degrees C was reached in 30 minutes. Saturation binding experiments and subsequent analysis of the results with Scatchard plots gave results consistent with the presence of a single saturable binding site. DMPC or POPC unilamellar vesicles could not compete with apoA-IV-DMPC for binding; apoA-I-DMPC competed only partially. ApoE-poor HDL effectively competed with apoA-IV-DMPC. The fact that binding could be greatly reduced (greater than 70%) by preincubating the membrane with pronase (18 micrograms/ml), supports the conclusion that a membrane protein is involved in binding. Based on these results, we speculate that the rapid catabolism of apoA-IV in plasma may be mediated by a specific uptake mechanism in the liver. The implications of these results support the hypothesis that apoA-IV is involved in reverse cholesterol transport.
已制备大鼠载脂蛋白 A-IV 与二肉豆蔻酰磷脂酰胆碱的复合物（apoA-IV-DMPC），并研究了其与纯化的大鼠肝细胞膜结合的能力。在 37℃下 30 分钟达到结合平衡。饱和结合实验以及随后用 Scatchard 图对结果进行分析，所得结果与存在单一可饱和结合位点一致。二肉豆蔻酰磷脂酰胆碱（DMPC）或 1-棕榈酰-2-油酰磷脂酰胆碱（POPC）单层囊泡不能与 apoA-IV-DMPC 竞争结合；载脂蛋白 A-I-DMPC 仅部分竞争。载脂蛋白 E 含量低的高密度脂蛋白（HDL）能有效与 apoA-IV-DMPC 竞争。用链霉蛋白酶（18 微克/毫升）预孵育细胞膜可使结合大幅减少（超过 70%），这一事实支持了膜蛋白参与结合的结论。基于这些结果，我们推测血浆中载脂蛋白 A-IV 的快速分解代谢可能由肝脏中的一种特异性摄取机制介导。这些结果的意义支持了载脂蛋白 A-IV 参与逆向胆固醇转运的假说。
