Receptor-mediated endocytosis of transferrin and recycling of the transferrin receptor in rat reticulocytes.
Receptor-mediated endocytosis of transferrin and recycling of the transferrin receptor in rat reticulocytes.
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DOI：
10.1083/jcb.97.2.329
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发表时间：
1983-08
期刊：
影响因子：
--
通讯作者：
Stahl P
中科院分区：
文献类型：
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作者：
Harding C;Heuser J;Stahl P
在4℃时，转铁蛋白与网织细胞细胞膜上的受体结合，在37℃时，受体介导的转铁蛋白内吞作用发生。37℃时的吸收比4℃时的结合多2.5倍，20- 30min后达到饱和。在37℃的摄取过程中，结合的转铁蛋白被内化到一个抵抗胰蛋白酶的空间。4℃胰蛋白酶化破坏了表面受体，但随后在37℃孵育，表面受体迅速出现（尽管数量减少），摄取水平下降。内吞作用后，转铁蛋白被释放，明显完整地进入细胞外空间。在37℃时，胶体金-转铁蛋白（AuTf）聚集在被涂覆的凹坑中，然后出现在细胞内各种有膜的隔室中。37℃孵育5-10分钟后，小泡和小管被标记，较大的多泡内体在孵育20-35分钟后被大量标记。多泡内体明显与质膜融合，并通过胞吐作用释放其内容物。这些细胞器都不是溶酶体性质的，98%的细胞内AuTf定位于酸性磷酸酶阴性的室室。与转铁蛋白一样，在37℃下孵育后，AuTf被释放。冷冻干燥和冷冻破裂的网状细胞证实了AuTf在网状细胞中的分布，并发现在质膜内表面的谱蛋白涂层中存在网格蛋白包被的斑块。这些数据表明，转铁蛋白通过被包裹的凹坑和囊泡被内化，并表明转铁蛋白及其受体在内吞作用后被循环回质膜。
At 4 degrees C transferrin bound to receptors on the reticulocyte plasma membrane, and at 37 degrees C receptor-mediated endocytosis of transferrin occurred. Uptake at 37 degrees C exceeded binding at 4 degrees C by 2.5-fold and saturated after 20-30 min. During uptake at 37 degrees C, bound transferrin was internalized into a trypsin- resistant space. Trypsinization at 4 degrees C destroyed surface receptors, but with subsequent incubation at 37 degrees C, surface receptors rapidly appeared (albeit in reduced numbers), and uptake occurred at a decreased level. After endocytosis, transferrin was released, apparently intact, into the extracellular space. At 37 degrees C colloidal gold-transferrin (AuTf) clustered in coated pits and then appeared inside various intracellular membrane-bounded compartments. Small vesicles and tubules were labeled after short (5-10 min) incubations at 37 degrees C. Larger multivesicular endosomes became heavily labeled after longer (20-35 min) incubations. Multivesicular endosomes apparently fused with the plasma membrane and released their contents by exocytosis. None of these organelles appeared to be lysosomal in nature, and 98% of intracellular AuTf was localized in acid phosphatase-negative compartments. AuTf, like transferrin, was released with subsequent incubation at 37 degrees C. Freeze-dried and freeze-fractured reticulocytes confirmed the distribution of AuTf in reticulocytes and revealed the presence of clathrin-coated patches amidst the spectrin coating the inner surface of the plasma membrane. These data suggest that transferrin is internalized via coated pits and vesicles and demonstrate that transferrin and its receptor are recycled back to the plasma membrane after endocytosis.