Endocytosis of the transferrin receptor requires the cytoplasmic domain but not its phosphorylation site |
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Authors: | S Rothenberger B J Iacopetta L C Kühn |
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Affiliation: | 1. Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China;2. Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China;1. Key Laboratory of East China Sea & Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, China;2. College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China;1. College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China;2. Zhejiang Ocean University, Zhoushan, 316022, China;3. Ningde Fufa Fisheries Co., LTD, Ningde, 352002, China;1. Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA;2. Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA;3. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA;4. Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA;5. Department of Cancer Biology and Blais Proteomics Center, Dana-Farber Cancer Institute, Boston, MA 02115, USA;6. Departments of Chemistry, Pharmacology, and Molecular, Cellular and Development Biology, Yale University, New Haven, CT 06511, USA;7. Chemical Kinomics Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136-791, Republic of Korea;8. KU-KIST Graduate School of Converging Science and Technology, Seongbuk-gu, Seoul 136-713, Republic of Korea;9. Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA |
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Abstract: | The transferrin receptor (TR) mediates cellular iron uptake by bringing about the endocytosis of transferrin. We investigated whether the cytoplasmic domain of 65 N-terminal amino acids or phosphorylated sites within this domain constitute a structure that is required for TR endocytosis. To test this hypothesis, we modified the cytoplasmic serine residues or introduced a deletion of 36 amino acids by in vitro mutagenesis of a cDNA expression vector for human TR. Upon expression in transfected mouse Ltk- cells, both the wild-type and phosphorylation site mutant receptors mediated transferrin internalization, whereas the truncated receptor did not. These results provide evidence that the cytoplasmic domain, or part of it, is essential for internalization of the TR, but argue against a role for receptor phosphorylation in endocytosis. |
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