Biomaterial Database

Presence of O-linked oligosaccharide on a threonine residue in the human transferrin receptor. 1992

S I Do, and R D Cummings

Department of Biochemistry, University of Georgia, Athens 30602.

We have previously demonstrated that the human transferrin receptor (TfR) of approximately 90 kDa contains Ser/Thr-linked (O-linked) oligosaccharides. In the present study, we report our identification of the site of attachment of the O-linked oligosaccharides in the receptor. A 70 kDa fragment from the external domain of the TfR was generated by trypsin treatment of the [3H]glucosamine-labelled receptor purified from human K562 cells. The beta-elimination of the intact TfR, but not the 70 kDa fragment, released Gal-[3H]Gal-NAcitol, indicating that the 70 kDa fragment lacks O-linked oligosaccharides. In the remaining 20 kDa fragment there are three potential sites (Thr96, Thr104 and Ser106) for O-glycosylation in the extracellular domain. To identify which of these residues are O-glycosylated, both the [3H]Thr- and [3H]Ser-labelled TfR were directly treated with mild base to effect beta-elimination, and the radiolabelled amino acids and their derivatives were analysed. Approximately 2% of the total radiolabelled Thr, but no radiolabelled Ser, was converted to expected beta-elimination products by this treatment. These and other results demonstrate that only one O-linked oligosaccharide is present in the TfR and that it occurs on either Thr96 or Thr104. From human serum we purified the cleaved, soluble form of the TfR (s-TfR), which contains Thr104, but lacks Thr96. The s-TfR was sensitive to O-glycanase and bound to Jacalin lectin, indicating that the s-TfR contains an O-linked oligosaccharide.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007163	Immunosorbent Techniques	Techniques for removal by adsorption and subsequent elution of a specific antibody or antigen using an immunosorbent containing the homologous antigen or antibody.	Immunoadsorbent Techniques,Immunoadsorbent Technics,Immunosorbent Technics,Immunoadsorbent Technic,Immunoadsorbent Technique,Immunosorbent Technic,Immunosorbent Technique,Technic, Immunoadsorbent,Technic, Immunosorbent,Technics, Immunoadsorbent,Technics, Immunosorbent,Technique, Immunoadsorbent,Technique, Immunosorbent,Techniques, Immunoadsorbent,Techniques, Immunosorbent
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009844	Oligosaccharides	Carbohydrates consisting of between two (DISACCHARIDES) and ten MONOSACCHARIDES connected by either an alpha- or beta-glycosidic link. They are found throughout nature in both the free and bound form.	Oligosaccharide
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011990	Receptors, Transferrin	Membrane glycoproteins found in high concentrations on iron-utilizing cells. They specifically bind iron-bearing transferrin, are endocytosed with its ligand and then returned to the cell surface where transferrin without its iron is released.	Transferrin Receptors,Transferrin Receptor,Receptor, Transferrin
D002236	Carbohydrate Conformation	The characteristic 3-dimensional shape of a carbohydrate.	Carbohydrate Linkage,Carbohydrate Conformations,Carbohydrate Linkages,Conformation, Carbohydrate,Conformations, Carbohydrate,Linkage, Carbohydrate,Linkages, Carbohydrate
D002240	Carbohydrate Sequence	The sequence of carbohydrates within POLYSACCHARIDES; GLYCOPROTEINS; and GLYCOLIPIDS.	Carbohydrate Sequences,Sequence, Carbohydrate,Sequences, Carbohydrate
D004915	Leukemia, Erythroblastic, Acute	A myeloproliferative disorder characterized by neoplastic proliferation of erythroblastic and myeloblastic elements with atypical erythroblasts and myeloblasts in the peripheral blood.	Di Guglielmo's Disease,Erythremic Myelosis,Erythroblastic Leukemia, Acute,Erythroleukemia,Leukemia, Myeloid, Acute, M6,Myeloid Leukemia, Acute, M6,Di Guglielmo Disease,Acute Erythroblastic Leukemia,Acute Erythroblastic Leukemias,Di Guglielmos Disease,Disease, Di Guglielmo,Disease, Di Guglielmo's,Erythremic Myeloses,Erythroblastic Leukemias, Acute,Erythroleukemias,Leukemia, Acute Erythroblastic,Leukemias, Acute Erythroblastic,Myeloses, Erythremic,Myelosis, Erythremic
D006031	Glycosylation	The synthetic chemistry reaction or enzymatic reaction of adding carbohydrate or glycosyl groups. GLYCOSYLTRANSFERASES carry out the enzymatic glycosylation reactions. The spontaneous, non-enzymatic attachment of reducing sugars to free amino groups in proteins, lipids, or nucleic acids is called GLYCATION (see MAILLARD REACTION).	Protein Glycosylation,Glycosylation, Protein