CO-LOCALIZATION OF I-125 EPIDERMAL GROWTH-FACTOR AND FERRITIN-LOW DENSITY LIPOPROTEIN IN COATED PITS - A QUANTITATIVE ELECTRON-MICROSCOPIC STUDY IN NORMAL AND MUTANT HUMAN-FIBROBLASTS
CO-LOCALIZATION OF I-125 EPIDERMAL GROWTH-FACTOR AND FERRITIN-LOW DENSITY LIPOPROTEIN IN COATED PITS - A QUANTITATIVE ELECTRON-MICROSCOPIC STUDY IN NORMAL AND MUTANT HUMAN-FIBROBLASTS
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DOI：
10.1083/jcb.95.1.73
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发表时间：
1982-01-01
影响因子：
7.8
通讯作者：
ORCI, L
中科院分区：
文献类型：
--
作者：
CARPENTIER, JL;GORDEN, P;ORCI, L
低密度脂蛋白（LDL）和表皮生长因子（EGF）与人成纤维细胞表面的受体结合，并内化到被膜血管中。每个配体分别研究了EM在人成纤维细胞使用铁蛋白-LDL作为1视觉探针和125 I-EGF作为第二视觉探针。人成纤维细胞的突变株（J.D.）其中LDL不定位于包被的小凹，因此不内化。由于LDL和EGF不相互竞争结合，在目前的研究中，将2种配体与正常和突变细胞共孵育，以观察它们的细胞命运。在正常的成纤维细胞中，铁蛋白-LDL和125 I-EGF都优先结合到4 °的包被小凹上。C和两种配体被内化到内吞囊泡和溶酶体中。在正常细胞中的定量研究表明，75%的包被坑和囊泡，含有125 I-EGF也含有铁蛋白-LDL，表明这两种配体进入细胞通过相同的内吞囊泡。在LDL内化突变型J.D.细胞，铁蛋白-LDL没有本地化，并没有内化，但125 I-EGF结合到包被的小窝和内化，就像在正常的成纤维细胞。
Low density lipoprotein (LDL) and epidermal growth factor (EGF) bind to receptors on the surface of human fibroblasts and are internalized in coated veiscles. Each of the ligands was studied separately by EM in human fibroblasts using ferritin-LDL as 1 visual probe and 125I-EGF as a 2nd visual probe. A mutant strain of human fibroblasts (J.D.) was described in which LDL does not localize to coated pits and therefore is not internalized. Because LDL and EGF do not compete with each other for binding, in the current studies the 2 ligands were coincubated with normal and mutant cells to visualize their cellular fates. In normal fibroblasts, ferritin-LDL and 125I-EGF both bound preferentially to coated pits at 4.degree. C and both ligands were internalized into endocytotic vesicles and lysosomes. Quantitative studies in normal cells showed that 75% of the coated pits and vesicles that contained 125I-EGF also contained ferritin-LDL, indicating that both ligands enter the cell through the same endocytotic vesicles. In the LDL internalization-mutant J.D. cells, ferritin-LDL did not localize in coated pits and was not internalized, but 125I-EGF bound to coated pits and was internalized just as in normal fibroblasts.