Processing of the Human Transferrin Receptor at Distinct Positions within the Stalk Region by Neutrophil Elastase and Cathepsin G
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Matthias Kaup
Abstract
The ectodomain of the human transferrin receptor (TfR) is released as soluble TfR into the blood by cleavage within a stalk. The major cleavage site is located Cterminally of Arg-100; alternative cleavage sites are also present. Since the cleavage process is still unclear, we looked for proteases involved in TfR ectodomain release. In the supernatant of U937 histiocytic cells we detected alternatively cleaved TfR (at Glu-110). In membrane fractions of these cells we identified two distinct proteolytic activities responsible for TfR cleavage within the stalk at either Val-108 or Lys-95. Both activities could be inhibited by serine protease inhibitors, but not by inhibitors of any other class of proteases. Protein purification yielded a 28 kDa protein that generated the Val-108 terminus. The protease activity could be ascribed to neutrophil elastase according to the substrate specificity determined by amino acid substitution analysis of synthetic peptides, an inhibitor profile, the size of the protease and the use of specific antibodies. The results of analogous experiments suggest that the second activity is represented by another serine protease, cathepsin G. Thus, membraneassociated forms of neutrophil elastase and cathepsin G may be involved in alternative TfR shedding in U937 cells.
Copyright © 2002 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Highlight: Environmental Mutagenesis
- DNA Double-Strand Break Repair by Homologous Recombination
- An Overview of the Analysis of DNA Methylation in Mammalian Genomes
- Methylation of the RASSF1A Gene in Human Cancers
- Exocyclic DNA Adducts as Oxidative Stress Markers in Colon Carcinogenesis: Potential Role of Lipid Peroxidation, Dietary Fat and Antioxidants
- DNA Polymorphisms as Modulators of Genotoxicity and Cancer
- Recent Aspects of Oxidative DNA Damage: Guanine Lesions, Measurement and Substrate Specificity of DNA Repair Glycosylases
- The Bacterial Regulatory Protein H-NS A Versatile Modulator of Nucleic Acid Structures
- Molecular Mechanisms of Nickel Carcinogenesis
- DNA Binding Properties of the Yeast Msh2-Msh6 and Mlh1-Pms1 Heterodimers
- N-Hydroxyarylamine O-Acetyltransferase-Deficient Escherichia coli Strains Are Resistant to the Mutagenicity of Nitro Compounds
- Functional Genomics of C190T Single Nucleotide Polymorphism in Human N-Acetyltransferase 2
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- Analysis of the Prion Protein in Primates Reveals a New Polymorphism in Codon 226 (Y226F)
- Inducibility of the Streptomyces traRts107-Ptra Expression Cassette in Mycobacterium smegmatis
