Sugita Y, Nakano Y, Tomita M
J Biochem. 1986 Nov;100(5):1193-200. doi: 10.1093/oxfordjournals.jbchem.a121823.
Mild trypsinization of human erythrocyte stroma solubilized CR1 (complement receptor type 1, C3b/C4b receptor) without significant loss of decay-accelerating activity to C5 convertases on hemolytic intermediate cells (EAC 1-3b, P). The solubilized CR1 was purified using DEAE-Sephacel, C3-Sepharose, and anti-CR1-Sepharose column chromatographies. The purified material showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing conditions, and its molecular weight was determined to be 175K, about 20K smaller than native CR1. Because the purified sample was separated into the several segments by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions, the molecule is considered to be nicked and those segments are associated by disulfide bonds. These results mean that a large portion of the CR1 molecule is present outside of the plasma membrane of erythrocytes, and the intramembranous and cytoplasmic domains are not necessary for decay-accelerating activity.
对人红细胞基质进行轻度胰蛋白酶处理可溶解CR1（补体受体1型，C3b/C4b受体），而对溶血中间细胞（EAC 1-3b，P）上的C5转化酶的衰变加速活性没有明显损失。使用DEAE-琼脂糖凝胶、C3-琼脂糖凝胶和抗CR1-琼脂糖凝胶柱色谱法对溶解的CR1进行纯化。在非还原条件下，纯化后的物质在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上显示出一条带，其分子量测定为175K，比天然CR1小约20K。由于在还原条件下，纯化后的样品在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳中被分离成几个片段，因此认为该分子有切口，这些片段通过二硫键相连。这些结果表明，CR1分子的大部分存在于红细胞质膜之外，膜内和细胞质结构域对于衰变加速活性并非必需。
