Pechak D G, Carrino D A, Caplan A I
J Cell Biol. 1985 May;100(5):1767-76. doi: 10.1083/jcb.100.5.1767.
In this article, proteoglycans from embryonic chick leg muscle are quantitatively and qualitatively compared with day 8 high density cell culture cartilage proteoglycans by electron microscopy of proteoglycan-cytochrome c monolayers. The visualized proteoglycan profiles were separated into four categories according to shape, size, and complexity. The two major categories were further characterized by lengths of core proteins, lengths of side projections, and distance between side projections. Two large proteoglycans are identifiable in spread leg muscle preparations. One group has a core protein (mean length of 205 nm) from which extend long thin side projections that we interpret to be groups of chondroitin sulfate glycosaminoglycans with a mean length of 79 nm. This large chondroitin sulfate proteoglycan is the only type found in muscle cultures as determined both biochemically in the past and now by electron microscopy and is referred to as muscle proteoglycan. The second large proteoglycan has a mean core protein length of 250 nm and side projections that are visibly shorter (mean length of 38 nm) and thicker than those of the muscle proteoglycan. This group is referred to as the mesenchymal proteoglycan since its biosynthetic origin is still uncertain. We compare these two profiles with the chick cartilage chondroitin sulfate proteoglycan that has a mean core protein length of 202 nm and side projections with a mean length of 50 nm. The data presented here substantiate the earlier biochemical characterization of these noncartilage proteoglycans and establish the unique structural features of the muscle proteoglycan as compared with the similar profiles of the cartilage and mesenchymal proteoglycans.
在本文中，通过对蛋白聚糖 - 细胞色素c单层进行电子显微镜观察，对来自胚胎鸡腿部肌肉的蛋白聚糖与第8天高密度细胞培养软骨蛋白聚糖进行了定量和定性比较。根据形状、大小和复杂性，将可视化的蛋白聚糖谱分为四类。两大主要类别进一步通过核心蛋白长度、侧突长度和侧突之间的距离来表征。在伸展的腿部肌肉制剂中可识别出两种大型蛋白聚糖。一组具有核心蛋白（平均长度为205纳米），从该核心蛋白伸出长而细的侧突，我们认为这些侧突是硫酸软骨素糖胺聚糖组，平均长度为79纳米。这种大型硫酸软骨素蛋白聚糖是过去通过生化方法以及现在通过电子显微镜确定的肌肉培养物中唯一发现的类型，被称为肌肉蛋白聚糖。第二种大型蛋白聚糖的核心蛋白平均长度为250纳米，其侧突明显比肌肉蛋白聚糖的侧突短（平均长度为38纳米）且厚。由于其生物合成起源仍不确定，该组被称为间充质蛋白聚糖。我们将这两种谱与鸡软骨硫酸软骨素蛋白聚糖进行比较，后者的核心蛋白平均长度为202纳米，侧突平均长度为50纳米。此处呈现的数据证实了这些非软骨蛋白聚糖早期的生化特征，并确定了与软骨和间充质蛋白聚糖相似谱相比，肌肉蛋白聚糖独特的结构特征。
