Choi-Miura N H, Sakamoto T, Tobe T, Nakano Y, Tomita M
Department of Physiological Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo.
J Biochem. 1993 Apr;113(4):484-7. doi: 10.1093/oxfordjournals.jbchem.a124070.
Soluble membrane attack complex (SMAC, SC5b-9) of complement contained apolipoprotein A-I (apo A-I) and lipids. Since SC5b-9 contained no apolipoprotein A-II (apo A-II), the incorporation of apo A-I and lipids into SC5b-9 was not caused by a non-specific binding of high-density lipoprotein (HDL). The incorporation of apo A-I into SC5b-9 was confirmed by a double agar diffusion immuno-assay. SC5b-9 contained one molecule of apo A-I and 3.5% lipids by weight. The composition of the lipids was phospholipid: total cholesterol: triglyceride = 47.5:45.0:7.5, and the ratio of free cholesterol:esterified cholesterol was 22.3:77.7. Since SC5b-7 contained apo A-I and SC5b-9 free of SP-40,40 contained no apo A-I, the HDL consisting of SP-40,40, apo A-I, and lipids was incorporated into SMAC at the stage of SC5b-7 via SP-40,40 as a binding site.
补体的可溶性膜攻击复合物（SMAC，SC5b-9）含有载脂蛋白A-I（apo A-I）和脂质。由于SC5b-9不含载脂蛋白A-II（apo A-II），因此apo A-I和脂质掺入SC5b-9并非由高密度脂蛋白（HDL）的非特异性结合所致。通过双向琼脂扩散免疫测定法证实了apo A-I掺入SC5b-9。SC5b-9按重量计含有一分子apo A-I和3.5%的脂质。脂质的组成是磷脂：总胆固醇：甘油三酯 = 47.5:45.0:7.5，游离胆固醇与酯化胆固醇的比例为22.3:77.7。由于SC5b-7含有apo A-I且不含SP-40,40的SC5b-9不含apo A-I，由SP-40,40、apo A-I和脂质组成的HDL在SC5b-7阶段通过SP-40,40作为结合位点掺入SMAC。
