【项目简介】
Trk A, the product of the protooncogene trk, is a member of the neurotrophic tyrosine kinase receptor family that has three members. Trk A, Trk B and Trk C preferentially bind NGF, NT4 and BDNF, and NT3, respectively. All Trk family proteins share a conserved complex subdomain organization consisting of a signal peptide, two cysteinerich
domains, a cluster of three leucinerich motifs, and two immunoglobulinlike domains in the extracellular region, as well as an intracellular region that contains the tyrosine kinase domain. Two distinct Trk A isoforms that differ by virtue of a 6amino acid insertion in their extracellular domain have been identified. The longer Trk A isoform is the only isoform expressed within neuronal tissues whereas the shorter Trk A is expressed mainly in nonneuronal tissues. NGF binds to Trk A with low affinity and activates its cytoplasmic kinase, initiating a signaling cascade that mediates neuronal survival and differentiation. Higher affinity binding of NGF requires the coexpression of Trk A with the p75 NGF receptor (NGFR), a member of the tumor necrosis factor receptor superfamily. 

【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TrkA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TrkA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TrkA抗体可与被酶标板捕获的人TrkA结合，形成“包被抗人TrkA抗体+人TrkA+抗人TrkA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TrkA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TrkA的浓度。