The molecular configuration and ultrastructural locations of an IgG Fc binding site in human colonic epithelium.
The molecular configuration and ultrastructural locations of an IgG Fc binding site in human colonic epithelium.
复制标题
人结肠上皮中 IgG Fc 结合位点的分子构型和超微结构位置。
DOI：
10.4049/jimmunol.146.1.68
复制
发表时间：
1991
影响因子：
4.4
通讯作者：
W. Brown
中科院分区：
文献类型：
--
作者：
K. Kobayashi;Y. Hamada;M. Blaser;W. Brown
此前，我们在人的小肠和结肠粘膜中发现了一个免疫球蛋白Fc区的结合部位。结合部位(Fc-γIBS)似乎主要与杯状细胞有关，由大于200,000 Da和78,000 Da的组分组成，与白细胞FCR不同。在目前的工作中，我们使用制备的mAb与结肠癌细胞免疫球蛋白结合，以更准确地确定Fc-Gamma IBS的分子结构和细胞位置。在免疫印迹和快速蛋白液相色谱分析中，mAb显示Fc-Gamma IBS除先前已知的两个组分外，还包括一个110,000-140,000-Da组分。大于200,000组分可能是免疫球蛋白与结肠片结合的关键成分，因为抗它的单抗而不是另外两个组分抑制免疫球蛋白与结肠切片的结合。免疫电子显微镜显示，FcγIBS存在于杯状细胞的内质网、分隔杯状细胞分泌颗粒的胞浆基质中以及颗粒内部，偶见与粘液一起分泌到肠腔内。Fc-γIBS不能被三种不同的去污剂溶解，表明它与细胞骨架元素形成络合物。我们推测，FcγIBS通过促进肠道粘液和肠腔内抗原物质之间的相互作用，有助于肠道的免疫保护。
Previously, we discovered a binding site for the Fc region of IgG in human small intestinal and colonic mucosa. The binding site (Fc gamma IBS) appeared to be primarily associated with goblet cells, to consist of greater than 200,000 Da and 78,000 Da components, and to be distinct from leukocyte FcR. In the present work, we used mAb made to colonocyte IgG-binding material to more accurately define the molecular structure and cellular locations of the Fc gamma IBS. In immunoblot and fast protein liquid chromatography analysis, the mAb revealed that the Fc gamma IBS consists of a 110,000- to 140,000-Da component in addition to the two components previously recognized. The greater than 200,000 component may be the critical component for IgG binding, inasmuch as mAb to it but not to the other two components inhibited binding of IgG to colonic sections in vitro. Used in immunoelectron microscopy, the mAb documented that the Fc gamma IBS is present in the endoplasmic reticulum of goblet cells, in the cytoplasmic matrix separating secretory granules of goblet cells, and within the granules themselves; occasionally it has the appearance of being secreted into the intestinal lumen with mucus. The Fc gamma IBS could not be solubilized from colonocyte homogenates by three different detergents, which suggests that it exists in complex with cytoskeletal elements. We speculate that the Fc gamma IBS aids in immunologic protection of the intestine by facilitating interaction between intestinal mucus and antigenic material in the lumen.