Oldberg A, Antonsson P, Lindblom K, Heinegård D
Department of Medical and Physiological Chemistry, University of Lund, Sweden.
J Biol Chem. 1992 Nov 5;267(31):22346-50.
Cloning and sequence analysis of cartilage oligomeric matrix protein (COMP) cDNA, representing a cartilage pentameric protein, revealed a protein of 755 amino acid residues with a calculated molecular mass of 82,700 Da. Expression of the cDNA in COS cells showed that COMP is a homopolymer composed of five identical disulfide-linked subunits. COMP is homologous to the carboxyl-terminal half of thrombospondin, and the homologies include 89% and 54% of the residues in COMP and thrombospondin, respectively. The similarities are most pronounced in the carboxyl-terminal domains and in the calcium binding type 3 repeat domains in which about 60% of the amino acid residues are identical. In the type 2/epidermal growth factor repeat domains the two proteins contain 41% identical residues. The sequence of the amino-terminal 84-amino acid residues is unique for COMP. Comparison of the amino acid sequences in the type 2 and type 3 repeat domains of COMP and the thrombospondins shows that COMP is the product of a unique gene and not the result of an alternatively spliced thrombospondin gene.
软骨寡聚基质蛋白（COMP）cDNA的克隆及序列分析表明，该蛋白为软骨五聚体蛋白，由755个氨基酸残基组成，计算分子量为82,700道尔顿。cDNA在COS细胞中的表达显示，COMP是由五个相同的二硫键连接亚基组成的同聚物。COMP与血小板反应蛋白的羧基末端一半同源，COMP和血小板反应蛋白的同源性分别包括89%和54%的残基。相似性在羧基末端结构域和钙结合3型重复结构域中最为明显，其中约60%的氨基酸残基相同。在2型/表皮生长因子重复结构域中，这两种蛋白质含有41%相同的残基。COMP氨基末端84个氨基酸残基的序列是独特的。COMP与血小板反应蛋白2型和3型重复结构域中氨基酸序列的比较表明，COMP是一个独特基因的产物，而不是血小板反应蛋白基因选择性剪接的结果。
