Receptor-mediated transport of IgG across the intestinal epithelium of the neonatal rat.
Receptor-mediated transport of IgG across the intestinal epithelium of the neonatal rat.
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DOI：
10.1002/9780470720745.ch11
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
R. Rodewald;D. Abrahamson
中科院分区：
文献类型：
--
作者：
R. Rodewald;D. Abrahamson
新生大鼠的吸收上皮在发育过程中专门负责将母体免疫球蛋白G(Ig G)原封不动地转移到循环中，而其他乳蛋白则被消化。负责免疫球蛋白转移的十二指肠和空肠近端上皮细胞为研究受体介导的细胞内转运提供了独特的实验模型。位于管腔质膜上的受体选择性地结合免疫球蛋白Fc区。免疫球蛋白通过包被囊泡中的结构性内吞作用进入细胞，然后在基侧质膜上释放。形态学证据支持这样一种模型，即免疫球蛋白以配体-受体复合体的形式穿过细胞，只有在细胞基侧表面发现的pH为7.4的环境中才会解离。虽然免疫球蛋白在管腔质膜上的摄取是高度选择性的，但少量但相当数量的其他蛋白质显然是非选择性地进入细胞的。然而，这些后一种蛋白质不会在细胞内转移。双示踪实验表明，免疫球蛋白和其他蛋白质在相同的内吞囊泡中同时进入细胞，但非膜结合蛋白被从免疫球蛋白转运途径中移除，其机制尚不清楚，并隔离在小的顶端空泡和溶酶体中。
The absorptive epithelium of the neonatal rat is developmentally specialized to transfer maternal immunoglobulin G (IgG) intact to the circulation while other milk protein are digested. The epithelial cells of the duodenum and proximal jejunum which are responsible for IgG transfer represent a particular striking experimental model for study of receptor-mediated intracellular transport. Receptors located on the luminal plasma membrane selectively bind the Fc region of IgG. The IgG enters the cell by constitutive endocytosis within coated vesicles and is then released at the basolateral plasma membrane. Morphological evidence supports a model in which IgG crosses the cell as a ligand-receptor complex that dissociates only on exposure to a pH 7.4 environment found at the basolateral cell surface. Although uptake of IgG at the luminal plasma membrane is highly selective, small but significant amounts of other proteins enter the cell apparently non-selectively. Nevertheless, these latter proteins are not transferred across the cell. Double-tracer experiments indicate that IgG and these other proteins enter the cell simultaneously within the same endocytic vesicles, but that non-membrane-bound proteins are removed from the IgG transport pathway by an as yet poorly defined mechanism and sequestered within small apical vacuoles and lysosomes.