Hauser N, Paulsson M
M. E. Müller Institute for Biomechanics, University of Bern, Switzerland.
J Biol Chem. 1994 Oct 14;269(41):25747-53.
Cartilage matrix protein (CMP), a major component of many types of cartilage, is a noncollagenous glycoprotein with a molecular mass of 148 kDa consisting of three identical subunits. With the aim of performing a more comprehensive characterization, we purified CMP in a native conformation from fetal bovine rib cartilage avoiding the denaturing solvents previously used. CMP could be selectively extracted with EDTA-containing buffer which indicates a divalent cation-dependent anchorage in the cartilage matrix. Determination of the amino-terminal sequence of the bovine protein confirmed its identity when compared with published cDNA sequences of chicken and human CMP. Electron microscopy revealed the presence of three ellipsoid subunits which are connected at one end. Sequence analysis indicated the presence of a coiled-coil alpha-helical assembly domain formed by the COOH-terminal end of the subunits. The trimeric structure was retained after complete reduction under native conditions which shows that the coiled-coil domain is stable also in the absence of interchain disulfide bonds.
软骨基质蛋白（CMP）是多种类型软骨的主要成分，是一种分子量为148 kDa的非胶原蛋白糖蛋白，由三个相同的亚基组成。为了进行更全面的表征，我们从胎牛肋软骨中以天然构象纯化了CMP，避免了先前使用的变性溶剂。CMP可以用含EDTA的缓冲液选择性提取，这表明它在软骨基质中以二价阳离子依赖的方式锚定。与已发表的鸡和人CMP的cDNA序列相比，牛蛋白氨基末端序列的测定证实了其身份。电子显微镜显示存在三个在一端相连的椭圆形亚基。序列分析表明，亚基的COOH末端形成了一个卷曲螺旋α-螺旋组装结构域。在天然条件下完全还原后，三聚体结构得以保留，这表明卷曲螺旋结构域在没有链间二硫键的情况下也是稳定的。
