Sommarin Y, Heinegård D
Biochem J. 1986 Feb 1;233(3):809-18. doi: 10.1042/bj2330809.
The characteristics of cell-associated proteoglycans were studied and compared with those from the medium in suspension cultures of calf articular-cartilage chondrocytes. By including hyaluronic acid or proteoglycan in the medium during [35S]sulphate labelling the proportion of cell-surface-associated proteoglycans could be decreased from 34% to about 15% of all incorporated label. A pulse-chase experiment indicated that this decrease was probably due to blocking of the reassociation with the cells of proteoglycans exported to the medium. Three peaks of [35S]sulphate-labelled proteoglycans from cell extracts and two from the medium were isolated by gel chromatography on Sephacryl S-500. These were characterized by agarose/polyacrylamide-gel electrophoresis, by SDS/polyacrylamide-gel electrophoresis of core proteins, by glycosaminoglycan composition and chain size as well as by distribution of glycosaminoglycans in proteolytic fragments. The results showed that associated with the cells were (a) large proteoglycans, typical for cartilage, apparently bound to hyaluronic acid at the cell surface, (b) an intermediate-size proteoglycan with chondroitin sulphate side chains (this proteoglycan, which had a large core protein, was only found associated with the cells and is apparently not related to the large proteoglycans), (c) a small proteoglycan with dermatan sulphate side chains with a low degree of epimerization, and (d) a somewhat smaller proteoglycan containing heparan sulphate side chains. The medium contained a large aggregating proteoglycan of similar nature to the large cell-associated proteoglycan and small proteoglycans with dermatan sulphate side chains with a higher degree of epimerization than those of the cells, i.e. containing some 20% iduronic acid.
研究了与细胞相关的蛋白聚糖的特性，并将其与来自小牛关节软骨软骨细胞悬浮培养物培养基中的蛋白聚糖特性进行了比较。在[35S]硫酸盐标记期间，通过在培养基中加入透明质酸或蛋白聚糖，细胞表面相关蛋白聚糖的比例可从所有掺入标记物的34%降至约15%。脉冲追踪实验表明，这种降低可能是由于阻止了分泌到培养基中的蛋白聚糖与细胞重新结合。通过Sephacryl S-500凝胶色谱法从细胞提取物中分离出三个[35S]硫酸盐标记的蛋白聚糖峰，从培养基中分离出两个峰。通过琼脂糖/聚丙烯酰胺凝胶电泳、核心蛋白的SDS/聚丙烯酰胺凝胶电泳、糖胺聚糖组成和链大小以及糖胺聚糖在蛋白水解片段中的分布对这些峰进行了表征。结果表明，与细胞相关的有：(a) 大型蛋白聚糖，典型的软骨型，显然在细胞表面与透明质酸结合；(b) 一种中等大小的蛋白聚糖，带有硫酸软骨素侧链（这种蛋白聚糖具有大的核心蛋白，仅在细胞中发现，显然与大型蛋白聚糖无关）；(c) 一种小型蛋白聚糖，带有硫酸皮肤素侧链，表异构化程度低；(d) 一种稍小的蛋白聚糖，含有硫酸乙酰肝素侧链。培养基中含有一种大型聚集蛋白聚糖，其性质与大型细胞相关蛋白聚糖相似，以及带有硫酸皮肤素侧链的小型蛋白聚糖，其表异构化程度高于细胞中的，即含有约20%的艾杜糖醛酸。
