de Bernard B
Clin Orthop Relat Res. 1982 Jan-Feb(162):233-44.
Glycoproteins in calcifiable matrices appear to play two different roles. As structural components, glycoproteins are associated with proteoglycans of which they share many properties and functions. In particular they are removed before the onset of calcification, therefore unmasking sites of calcium and phosphate deposition. As calcium and/or phosphate binding sites, glycoproteins appear to be associated with the mechanism of calcification. Glycoproteins may aid in transporting calcium and phosphate from points of initial deposition into the relatively inaccessible sites of mineralization. It is possible to assume also a nucleating effect and it cannot be excluded that Ca-binding glycoproteins are components of the "crystal ghosts." Glycoproteins also modulate calcium dependent phosphatase and ATPase activities. The recent discovery of an ATP-driven calcium pump associated with the plasma membrane of chondrocytes and the previous finding of an ATPase activity associated with the cartilage calcium-binding glycoprotein suggest that reduction in ATP content in matrix vesicles may be responsible for the initial deposits of mineral.
可钙化基质中的糖蛋白似乎发挥着两种不同的作用。作为结构成分，糖蛋白与蛋白聚糖相关联，它们具有许多共同的特性和功能。特别是在钙化开始之前它们会被去除，从而暴露钙和磷酸盐沉积的位点。作为钙和/或磷酸盐结合位点，糖蛋白似乎与钙化机制相关。糖蛋白可能有助于将钙和磷酸盐从初始沉积点转运到相对难以到达的矿化位点。也可以假定存在成核作用，并且不能排除钙结合糖蛋白是“晶体幽灵”的组成部分。糖蛋白还调节钙依赖性磷酸酶和ATP酶的活性。最近发现与软骨细胞的质膜相关的ATP驱动钙泵以及先前发现的与软骨钙结合糖蛋白相关的ATP酶活性表明，基质小泡中ATP含量的降低可能是矿物质初始沉积的原因。
