Shalev A, Gerrard J M, Robertson C, Greenberg A H, Linial M
Manitoba Institute of Cell Biology, Department of Pediatrics, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
J Cell Biochem. 1992 May;49(1):59-65. doi: 10.1002/jcb.240490111.
The immunological crossreactivity between the two granule-specific membrane glycoproteins, synaptophysin and granulophysin, was studied using a series of site-specific monoclonal and polyclonal antibodies. The epitope relatedness of six monoclonal antibodies against granulophysin was examined by competitive ELISA. The antibodies are shown to recognize distinct, but overlapping epitopes within a compact region that is constructed by the three-dimensional configuration of the molecule. All these antibody clones also recognize rat neuronal synaptophysin. Two monoclonal antibodies against synaptophysin, of which one is the well-characterized SY38 antibody, directed against the carboxy terminal of the molecule, are also shown to react with granulophysin. Characterized polyclonal antibodies against different peptide antigens of synaptophysin failed to recognize granulophysin. Synaptophysin and granulophysin are distinctly recognized in brain cell (white matter) and the pituitary both qualitatively and quantitatively. Based on these and other observations, it is suggested that the repeat motif in the cytoplasmic tail of synaptophysin represents an immunodominant construct that is the target for the observed crossreactive antibodies and that a similar tertiary construct has been preserved in granulophysin and in other transmembrane proteins.
利用一系列位点特异性单克隆抗体和多克隆抗体，研究了两种颗粒特异性膜糖蛋白——突触囊泡蛋白和颗粒体蛋白之间的免疫交叉反应性。通过竞争性酶联免疫吸附测定（ELISA）检测了六种抗颗粒体蛋白单克隆抗体的表位相关性。结果显示，这些抗体识别的是由分子三维结构构建的紧密区域内不同但重叠的表位。所有这些抗体克隆也识别大鼠神经元突触囊泡蛋白。两种抗突触囊泡蛋白的单克隆抗体（其中一种是已充分表征的针对分子羧基末端的SY38抗体）也显示与颗粒体蛋白发生反应。针对突触囊泡蛋白不同肽抗原的表征多克隆抗体未能识别颗粒体蛋白。在脑细胞（白质）和垂体中，突触囊泡蛋白和颗粒体蛋白在定性和定量方面都能被明确识别。基于这些及其他观察结果，有人提出，突触囊泡蛋白胞质尾中的重复基序代表一种免疫显性结构，是所观察到的交叉反应性抗体的靶标，并且类似的三级结构在颗粒体蛋白和其他跨膜蛋白中得以保留。
