Innate Immunology Group, National Veterinary Institute, Technical University of Denmark, Frederiksberg, Denmark.
PLoS One. 2013 Jul 2;8(7):e68110. doi: 10.1371/journal.pone.0068110. Print 2013.
The serum protein α1-acid glycoprotein (AGP), also known as orosomucoid, is generally described as an archetypical positive acute phase protein. Here, porcine AGP was identified, purified and characterized from pooled pig serum. It was found to circulate as a single chain glycoprotein having an apparent molecular weight of 43 kDa by SDS-PAGE under reducing conditions, of which approximately 17 kDa were accounted for by N-bound oligosaccharides. Those data correspond well with the properties of the protein predicted from the single porcine AGP gene (ORM1, Q29014 (UniProt)), containing 5 putative glycosylation sites. A monoclonal antibody (MAb) was produced and shown to quantitatively and specifically react with all microheterogenous forms of pig AGP as analyzed by 2-D electrophoresis. This MAb was used to develop an immunoassay (ELISA) for quantification of AGP in pig serum samples. The adult serum concentrations of pig AGP were in the range of 1-3 mg/ml in a number of conventional pig breeds while it was lower in Göttingen and Ossabaw minipigs (in the 0.3 to 0.6 mg/ml range) and higher in young (2-5 days old) conventional pigs (mean: 6.6 mg/ml). Surprisingly, pig AGP was found to behave as a negative acute phase protein during a range of experimental infections and aseptic inflammation with significant decreases in serum concentration and in hepatic ORM1 expression during the acute phase response. To our knowledge this is the first description in any species of AGP being a negative acute phase protein.
血清蛋白 α1-酸性糖蛋白（AGP），也称为乳白蛋白，通常被描述为典型的急性相蛋白。在这里，从混合猪血清中鉴定、纯化和表征了猪 AGP。发现它作为一种单链糖蛋白循环，在还原条件下通过 SDS-PAGE 电泳的表观分子量为 43 kDa，其中约 17 kDa 由 N 结合寡糖组成。这些数据与从单个猪 AGP 基因（ORM1，Q29014（UniProt））预测的该蛋白的性质非常吻合，该基因包含 5 个潜在的糖基化位点。产生了一种单克隆抗体（MAb），并通过 2-D 电泳分析表明它可定量且特异性地与猪 AGP 的所有微异质形式反应。该 MAb 用于开发用于定量猪血清样品中 AGP 的免疫测定（ELISA）。在一些常规猪品种中，成年猪血清 AGP 浓度在 1-3 mg/ml 范围内，而在哥廷根和 Ossabaw 小型猪中浓度较低（0.3 至 0.6 mg/ml 范围内），在年轻（2-5 天）的常规猪中浓度较高（平均值：6.6 mg/ml）。令人惊讶的是，在一系列实验性感染和无菌性炎症中，猪 AGP 表现为负急性相蛋白，在急性相反应期间血清浓度和肝 ORM1 表达显著降低。据我们所知，这是在任何物种中首次描述 AGP 为负急性相蛋白。
