Blight G D, Morgan E H
Biochim Biophys Acta. 1987 Jun 15;929(1):18-24. doi: 10.1016/0167-4889(87)90236-9.
Transferrin and ferritin endocytosis and exocytosis by guinea-pig reticulocytes were studied using incubation with pronase at 4 degrees C to distinguish internalized and membrane-bound protein. Internalization of both transferrin and ferritin occurred in a time- and temperature-dependent fashion. Transferrin endocytosis was more rapid than that of ferritin. Transferrin binding to receptors was not altered, but transferrin endocytosis was decreased in the presence of ferritin. Iron accumulation from transferrin was inhibited by ferritin to a greater extent than could be accounted for by the decreased rate of endocytosis. In pulse-chase experiments, almost all of the transferrin was released intact from reticulocytes, but only about 50% of the total internalized ferritin was released, of which 85% was intact. The endocytosis of transferrin by rabbit reticulocytes was 2- to 2.5-times faster than guinea-pig reticulocytes. These data suggest that ferritin and transferrin are internalized by receptor-mediated endocytosis, possibly involving the same coated pits and vesicles, but that the proteins are recycled only partly in common.
通过在4℃下用链霉蛋白酶孵育，研究了豚鼠网织红细胞对转铁蛋白和铁蛋白的内吞作用及胞吐作用，以区分内化蛋白和膜结合蛋白。转铁蛋白和铁蛋白的内化均呈时间和温度依赖性。转铁蛋白的内吞作用比铁蛋白更快。转铁蛋白与受体的结合未改变，但在铁蛋白存在的情况下转铁蛋白的内吞作用降低。铁蛋白对转铁蛋白中铁积累的抑制作用比内吞作用速率降低所能解释的程度更大。在脉冲追踪实验中，几乎所有的转铁蛋白都完整地从网织红细胞中释放出来，但内化的铁蛋白总量中只有约50%被释放，其中85%是完整的。兔网织红细胞对转铁蛋白的内吞作用比豚鼠网织红细胞快2至2.5倍。这些数据表明，铁蛋白和转铁蛋白通过受体介导的内吞作用内化，可能涉及相同的有被小窝和小泡，但这些蛋白质只有部分共同参与再循环。
