DISTRIBUTION OF IMMUNOGLOBULIN-G RECEPTORS IN THE SMALL-INTESTINE OF THE YOUNG-RAT
DISTRIBUTION OF IMMUNOGLOBULIN-G RECEPTORS IN THE SMALL-INTESTINE OF THE YOUNG-RAT
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DOI：
10.1083/jcb.85.1.18
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发表时间：
1980-01-01
影响因子：
7.8
通讯作者：
RODEWALD, R
中科院分区：
文献类型：
--
作者：
RODEWALD, R
使用辣根过氧化物酶 (HRP) 和免疫球蛋白 [Ig] G 的缀合物绘制可在 0°C 结合 IgG 的细胞表面受体的分布图。 C 位于 10-12 天龄大鼠的小肠内。管腔受体仅存在于十二指肠和近端空肠内。在这些位置，受体仅限于排列在单个绒毛上部的吸收细胞。在绒毛尖端附近，受体相对均匀地分布在整个管腔质膜上。在绒毛的中部区域，受体在管腔表面上分布不均匀。受体特异性结合大鼠和兔 IgG，识别 Ig 的 Fc 部分，并在 pH 6.0 时结合，但在 pH 7.4 时不结合。为了确定 IgG 受体是否局限于质膜的管腔部分，从 10-12 天龄大鼠的近端肠分离完整的上皮细胞，并在 0°C 下与 HRP 缀合物一起孵育。 C. 大鼠 IgG-HRP 在 pH 6.0 下与细胞的特异性结合表明 IgG 受体（其功能与腔表面上发现的那些受体相似）也存在于吸收性细胞的整个腔外表面上。这些结果与 IgG 以囊泡表面 IgG 受体复合物的形式转运至腔外质膜一致。这些复合物暴露于浆膜血浆（pH 值大概为 7.4）会导致 IgG 从受体中释放。为了评估 IgG、i.v. 排出后囊泡可能从管腔表面向内移动的情况。注射的 HRP 用作浆膜血浆中的空间填充示踪剂。 HRP 可以在负责 IgG 反向运输的包被囊泡和管状囊泡内可视化。这些囊泡可能提供受体在细胞的腔表面和近腔表面之间穿梭的途径。
Conjugates of horseradish peroxidase (HRP) and immunoglobulin [Ig] G were used to map the distribution of cell surface receptors that can bind IgG at 0.degree. C within the small intestine of 10-12 day old rats. Luminal receptors are present only within the duodenum and proximal jejunum. In these locations, receptors are limited to absorptive cells that line the upper portion of individual villi. Near villus tips, receptors are relatively evenly distributed over the entire luminal plasmalemma. In the midregion of villi, receptors are unevenly distributed over the luminal surface. Receptors specifically bind rat and rabbit IgG, recognize the Fc portion of the Ig and bind at pH 6.0 but not pH 7.4. To determine whether IgG receptors are confined to the luminal portion of the plasmalemma, intact epithelial cells were isolated from the proximal intestine of 10-12 day old rats and incubated with HRP conjugates at 0.degree. C. The specific binding of rat IgG-HRP to cells at pH 6.0 indicates that IgG receptors, which are functionally similar to those found on the luminal surface, are also present over the entire abluminal surface of absorptive cells. These results are consistent with the transport of IgG to the abluminal plasma membrane in the form of IgG-receptor complexes on the surface of vesicles. Exposure of these complexes to the serosal plasma, which is presumably at pH 7.4, would cause release of IgG from the receptors. To assess possible inward movement of vesicles from the abluminal surface after discharge of IgG, i.v. injected HRP was used as a space-filling tracer in the serosal plasma. HRP could be visualized within the coated and tubular vesicles responsible for transport of IgG in the opposite direction. These vesicles may provide a pathway whereby receptors shuttle between the luminal and abluminal surfaces of cells.