Johnstone B, Markopoulos M, Neame P, Caterson B
Department of Surgery, University of North Carolina, Chapel Hill 27599.
Biochem J. 1993 Jun 15;292 ( Pt 3)(Pt 3):661-6. doi: 10.1042/bj2920661.
Immunological studies revealed the presence of several different forms of biglycan and decorin in human intervertebral-disc tissues (annulus fibrosus, nucleus pulposus and cartilage end-plate). In the young intervertebral disc, glycosaminoglycan-containing (glycanated) forms of both biglycan and decorin represented a greater proportion of the total proteoglycan population present in extracts of annulus fibrosus and cartilage end-plate compared with extracts of nucleus pulposus, in which they were barely detectable. In older discs the glycanated forms of biglycan and decorin represented only a small proportion of the total proteoglycan present. Immunochemical analyses with an antibody to chondroitin/dermatan sulphate isomers indicated differences in the glycosaminoglycans substituted on glycanated forms of small proteoglycans found in different disc tissues. Dermatan sulphate was the predominant glycosaminoglycan present on biglycan and decorin in annulus fibrosus extracts, whereas chondroitin 4-sulphate was present in both small proteoglycans isolated from cartilage end-plate. In addition, immunochemical analyses with antibodies against core protein epitopes identified two non-glycanated forms of both biglycan and decorin. These non-glycanated forms of the small proteoglycans were found in all three regions of the disc. The two nonglycanated forms of biglycan had estimated molecular masses of 37 and 41 kDa and those of decorin were 43 and 45 kDa, respectively. These non-glycanated forms of biglycan and decorin increased in proportion with aging. N-terminal sequence analysis indicated that the larger non-glycanated form of decorin was a degradation product of its glycanated precursor. However, no N-terminal sequence information was obtainable from the other non-glycanated form of decorin or the two non-glycanated forms of biglycan. These data are consistent with the hypothesis that some of the non-glycanated forms of decorin and biglycan are degradation products of native precursors. However, the possibility remains that several different post-translationally modified forms of decorin and biglycan are synthesized by intervertebral-disc tissues.
免疫学研究表明，在人类椎间盘组织（纤维环、髓核和软骨终板）中存在几种不同形式的双糖链蛋白聚糖和核心蛋白聚糖。在年轻的椎间盘中，与髓核提取物相比，纤维环和软骨终板提取物中含糖胺聚糖（糖化）形式的双糖链蛋白聚糖和核心蛋白聚糖在总蛋白聚糖群体中所占比例更大，而在髓核提取物中它们几乎检测不到。在较老的椎间盘中，双糖链蛋白聚糖和核心蛋白聚糖的糖化形式仅占总蛋白聚糖的一小部分。用抗硫酸软骨素/硫酸皮肤素异构体抗体进行的免疫化学分析表明，在不同椎间盘组织中发现的小蛋白聚糖糖化形式上取代的糖胺聚糖存在差异。硫酸皮肤素是纤维环提取物中双糖链蛋白聚糖和核心蛋白聚糖上存在的主要糖胺聚糖，而硫酸软骨素4-硫酸酯存在于从软骨终板分离的两种小蛋白聚糖中。此外，用针对核心蛋白表位的抗体进行的免疫化学分析鉴定出双糖链蛋白聚糖和核心蛋白聚糖的两种非糖化形式。这些小蛋白聚糖的非糖化形式在椎间盘的所有三个区域中都有发现。双糖链蛋白聚糖的两种非糖化形式估计分子量分别为37 kDa和41 kDa，核心蛋白聚糖的两种非糖化形式估计分子量分别为43 kDa和45 kDa。双糖链蛋白聚糖和核心蛋白聚糖的这些非糖化形式的比例随年龄增长而增加。N端序列分析表明，较大的非糖化形式的核心蛋白聚糖是其糖化前体的降解产物。然而，无法从核心蛋白聚糖的另一种非糖化形式或双糖链蛋白聚糖的两种非糖化形式获得N端序列信息。这些数据与以下假设一致，即核心蛋白聚糖和双糖链蛋白聚糖的一些非糖化形式是天然前体的降解产物。然而，椎间盘组织仍有可能合成几种不同的翻译后修饰形式的核心蛋白聚糖和双糖链蛋白聚糖。
