Schwartz N B, Habib G, Campbell S, D'Elvlyn D, Gartner M, Krueger R, Olson C, Philipson L
Fed Proc. 1985 Feb;44(2):369-72.
Studies of the structure and synthesis of cartilage proteoglycan core protein have been carried out. Deglycosylation of completed, secreted proteoglycan by HF-pyridine treatment yielded an intact homogeneous core protein of approximately 210,000 daltons, with a blocked amino-terminus. Greater than 95% of chondroitin sulfate chains and 80% of N- and O-linked oligosaccharides were removed by the procedure, which made the product an excellent xylosyltransferase acceptor. Little alteration of core protein structure occurred during the HF-pyridine treatment as shown by complete immunoreactivity with antiserums prepared against hyaluronidase-digested proteoglycan. In other studies, the initially synthesized precursor for proteoglycan core protein was found to be approximately 376,000 daltons and localized to the rough membrane fractions. This precursor already contained N-linked oligosaccharides, and was also able to accept xylose, thereby initiating chondroitin sulfate chains. The precursor was translocated intact in an energy-dependent manner to smooth membrane-Golgi fractions where further processing of high mannose type of oligosaccharides and addition of glycosaminoglycan chains occurred. The subcellular distribution pattern of the chondroitin sulfate-synthesizing enzymes corroborated the proposed topological modifications of the proteoglycan core protein precursor.
对软骨蛋白聚糖核心蛋白的结构和合成进行了研究。通过HF-吡啶处理对完整的、分泌型蛋白聚糖进行去糖基化，得到了一种完整的、均一的、分子量约为210,000道尔顿的核心蛋白，其氨基末端被封闭。该方法去除了超过95%的硫酸软骨素链以及80%的N-连接和O-连接寡糖，使得产物成为一种优良的木糖基转移酶受体。如用针对透明质酸酶消化的蛋白聚糖制备的抗血清进行完全免疫反应所显示的，在HF-吡啶处理过程中核心蛋白结构几乎没有改变。在其他研究中，发现蛋白聚糖核心蛋白最初合成的前体分子量约为376,000道尔顿，并定位于粗面膜部分。该前体已经含有N-连接寡糖，并且还能够接受木糖，从而起始硫酸软骨素链。前体以能量依赖的方式完整地转运至滑面膜-高尔基体部分，在那里发生高甘露糖型寡糖的进一步加工以及糖胺聚糖链的添加。硫酸软骨素合成酶的亚细胞分布模式证实了所提出的蛋白聚糖核心蛋白前体的拓扑修饰。
