【项目简介】
β4GalT1 is one of seven β1,4 galactosyltransferases that transfer galactose in a β1,4 linkage to acceptor sugars including GlcNAc, and Glc, and Xyl. By sequence similarity, the β4GalTs form four groups: β4GalT1 and β4GalT2, β4GalT3 and β4GalT4, β4GalT5 and β4GalT6, and β4GalT7 . β4GalT1 is unique among the seven enzymes because it can be expressed either as membrane associated form or secreted form . The secreted form is restricted to lactating mammary tissues where the enzyme forms a heterodimer with αlactalbumin to catalyze the synthesis of lactose . The membrane form can reside either in the Golgi apparatus, where it adds galactose to Nacetylglucosamine residues, or on cell surface, where it functions as a recognition molecule during a variety of cell to cell and cell to matrix interactions, by binding to specific oligosaccharide ligands on opposing cells or in the extracellular matrix . The two enzymatic forms result from alternate transcription initiation sites and posttranslational processing . Defects in β4GalT1 are the cause of congenital disorder of glycosylation type 2D (CDG2D) . The activity of this enzyme has been measured with a phosphatasecoupled method .

【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β4GalT1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β4GalT1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β4GalT1抗体可与被酶标板捕获的人β4GalT1结合，形成“包被抗人β4GalT1抗体+人β4GalT1+抗人β4GalT1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β4GalT1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β4GalT1的浓度。