Chemical characterization of cell-CAM 105, a cell-adhesion molecule isolated from rat liver membranes.
Chemical characterization of cell-CAM 105, a cell-adhesion molecule isolated from rat liver membranes.
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细胞 CAM 105（一种从大鼠肝膜中分离出来的细胞粘附分子）的化学表征。
DOI：
10.1042/bj2360559
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
B. Obrink
中科院分区：
文献类型：
--
作者：
P. Odin;A. Tingström;B. Obrink
Cell-CAM 105是一种参与体外大鼠肝细胞识别和粘附的糖蛋白，通过免疫亲和层析、凝胶排阻层析和离子交换层析的组合纯化至均一。进行了电泳，成分和酶分析，糖蛋白被证明是由两个肽链，表观Mr分别为110，000和105，000，这是糖基化到类似的程度。碳水化合物分析表明存在唾液酸、半乳糖、甘露糖、岩藻糖和葡糖胺，但不存在半乳糖胺，表明仅存在N-连接寡糖。碳水化合物总含量为33%。肽图谱表明，这两条肽链在结构上非常相似。培养的肝细胞与[32 P]Pi孵育后，可分离磷酸化的细胞CAM 105。两条肽链都被标记，磷酸氨基酸分析表明丝氨酸残基已被磷酸化。细胞-CAM 105的一个显著特征是对难以抑制的自溶降解的敏感性。主要降解产物的表观Mr分别为90，000和70，000。研究了纯化的细胞-CAM 105对再聚集肝细胞的细胞-细胞粘附的影响。观察到显著的抑制，表明该蛋白直接参与这些细胞的细胞间粘附。
Cell-CAM 105, a glycoprotein that is involved in recognition and adhesion between isolated rat hepatocytes in vitro, was purified to homogeneity by a combination of immunoaffinity chromatography, gel-exclusion chromatography and ion-exchange chromatography. Electrophoretic, compositional and enzymic analyses were performed and the glycoprotein was shown to consist of two peptide chains, of apparent Mr 110,000 and 105,000 respectively, that are glycosylated to similar extents. Carbohydrate analyses demonstrated the presence of sialic acid, galactose, mannose, fucose and glucosamine, but no galactosamine, indicating that only N-linked oligosaccharides occurred. The total content of carbohydrate amounted to 33%. Peptide mapping indicated that the two peptide chains were structurally very similar. After incubation of cultured hepatocytes with [32P]Pi, phosphorylated cell-CAM 105 could be isolated. Both peptide chains were labelled and phospho-amino-acid analysis demonstrated that serine residues had become phosphorylated. A significant feature of cell-CAM 105 was a susceptibility to autolytic degradation that was difficult to inhibit. The major degradation products had apparent Mr 90,000 and 70,000, respectively. The effect of purified cell-CAM 105 on cell-cell adhesion of re-aggregating hepatocytes was studied. A significant inhibition was observed, indicating that the protein is directly involved in intercellular adhesion of these cells.