【项目简介】
The type I class A macrophage scavenger receptor (SRAI; also MSRAI) is a 70-80 kDa protein that belongs to an ever expanding family of transmembrane molecules collectively referred to as scavenger receptors. Receptors of this family contain characteristic extracellular domains and bind to a series of generally unrelated, but negatively-charged/ polyanionic ligands. Human SR-AI is a type II transmembrane glycoprotein that is 451 amino acids (aa) in length. It contains a 50 aa cytoplasmic tail, a 26 aa transmembrane segment and a 375 aa extracellular region. The extracellular region contains four definitive domains, with a membrane proximal spacer of 33 aa, an αhelical coiledcoil domain of 163 aa, a collagenlike domain of 69 aa, and a cysteinerich Cterminus of 110 aa. The cysteinerich domain (CRD) forms three intrachain disulfide bonds. The functional form of the molecule is a 220-230 kDa membraneassociated trimer that, in human, apparently has two disulfide bonded chains and a third noncovalently associated subunit. Human extracellular region is 73% and 72% aa identical to bovine and mouse SRAI extracellular region, respectively. The human gene for SRA gives rise to three isoforms; the I isoform of 451 aa, the II isoform of 358 aa, and the III isoform of 388 aa. 
 
【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人MSR I抗体，当加入标准品和待测样本时，标准品和待测样本中的人MSR I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人MSR I抗体可与被酶标板捕获的人MSR I结合，形成“包被抗人MSR I抗体+人MSR I+抗人MSR I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，人MSR I浓度与OD450值之间呈正比，可通过绘制标准曲线求出标本中人MSR I的浓度。