【项目简介】
Osteoadherin (OSAD), also known as Osteomodulin, is an extracellular matrix keratan sulfate proteoglycan that belongs to the class II subfamily of small leucine-rich proteoglycans (SLRP). LRR motifs consist of approximately 20 - 30 amino acids (aa) with conserved leucine spacing, folded into a structure with one beta -sheet and one alpha -helix. The mouse OSAD cDNA encodes a 423 aa precursor that contains a 20 aa signal sequence and twelve tandem leucine rich repeats. Mouse OSAD shares 75%, 79%, and 91% aa sequence identity with bovine, human, and rat OSAD, respectively. Mouse OSAD shares 32 - 35% aa sequence identity with mouse class II SLRPs Fibromodulin, Keratocan, Lumican, and PRELP. Bovine, mouse, and rat OSAD are expressed as 60 - 85 kDa molecules, even though the amino acid sequence for each predicts a size of 46 - 47 kDa. The primary difference is due to the presence of extensive N-linked glycosylation that can vary between tissues of the same species. Human OSAD is expressed as an even larger 110 kDa molecule in teeth. OSAD contains eight sulfated tyrosine residues and is distinguished from other class II SLRPs by the presence of an approximately 70 aa C-terminal acidic domain. 
 
【检验原理】
本试剂盒采用双抗体夹心ELISA法。酶标微孔板上预包被有抗小鼠Osteomodulin抗体，当加入标准品和待测样本时，标准品和待测样本中的小鼠Osteomodulin会和该抗体结合。洗板后，游离的其他成分被洗去，加入辣根过氧化物酶标记的的抗小鼠Osteomodulin抗体可与被酶标板捕获的小鼠Osteomodulin结合，形成“包被抗小鼠Osteomodulin抗体+小鼠Osteomodulin+抗小鼠Osteomodulin抗体-HRP”免疫复合物。当加入TMB显色底物后，复合物上连接的HRP催化底物反应，生成蓝色产物，终止反应后变为黄色。在450nm处测定OD值，小鼠Osteomodulin浓度与OD450值之间呈正比，可通过绘制标准曲线求出标本中小鼠Osteomodulin的浓度。