Structural model of phospholipid-reconstituted human transferrin receptor derived by electron microscopy

Fuchs, Hendrik; Lücken, Uwe; Tauber, Rudolf; Engel, Andréas; Geßner, Reinhard

doi:10.1016/s0969-2126(98)00124-5

Cited by 58 publications

(36 citation statements)

References 43 publications

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“…Each polypeptide is divided into a large C-terminal extracellular domain of 672 amino acids, a transmembrane domain of 21 amino acids, and an N-terminal cytoplasmic domain of 67 amino acids. The extracellular domain that binds Tf is kept by a juxtamembrane stalk at 2.9 nm from the plasma membrane (1). Within the stalk Thr-104 is O-glycosylated (2, 3), but detailed structure and function of the stalk remain unknown.…”

Section: The Transferrin Receptor (Tfr)mentioning

confidence: 99%

Shedding of the Transferrin Receptor Is Mediated Constitutively by an Integral Membrane Metalloprotease Sensitive to Tumor Necrosis Factor α Protease Inhibitor-2

Kaup¹,

Dassler²,

Weise³

et al. 2002

Journal of Biological Chemistry

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The transferrin receptor (TfR) is a transmembrane protein that mediates cellular uptake of iron. Although the serum concentration of the soluble TfR (sTfR) is altered in several diseases and used for diagnostic purposes, the identity and regulation of the shedding protease is unknown. In this study we quantified sTfR release from microsomal membranes and leukocytic cell lines in the presence of numerous protease inhibitors and cell activating compounds. We show that sTfR release is mediated by an integral membrane metalloprotease and can be inhibited by matrix metalloproteinase inhibitor 2 and tumor necrosis factor ␣ protease inhibitor-2 (TAPI-2). Cleavage is also inhibited by a specific furin inhibitor, indicating that the protease is activated by a furin-like proprotein convertase. Whereas stimulation of the cells by the ectodomain shedding activator phorbol 12-N-myristate 13-acetate did not alter sTfR release significantly, the phosphatase inhibitor pervanadate led to an increase of TfR shedding in several leukocytic cell lines. Our results suggest that TfR shedding is constitutively mediated by a member of the metalloprotease family known as ADAM (for a disintegrin and metalloprotease).The transferrin receptor (TfR) 1 is a type II transmembrane protein that mediates uptake of iron by binding the iron carrier protein transferrin (Tf). Following internalization of the complex, iron is released in the acidic endosomes and the TfR⅐Tf complex recycles back to the cell surface where apotransferrin is released at neutral pH. The TfR is composed of two homologous peptide chains of 760 amino acids linked by two disulfide bonds (Cys-89 and Cys-98) close to the transmembrane domain. Each polypeptide is divided into a large C-terminal extracellular domain of 672 amino acids, a transmembrane domain of 21 amino acids, and an N-terminal cytoplasmic domain of 67 amino acids. The extracellular domain that binds Tf is kept by a juxtamembrane stalk at 2.9 nm from the plasma membrane (1). Within the stalk Thr-104 is O-glycosylated (2, 3), but detailed structure and function of the stalk remain unknown.Although the appearance of the soluble form of the transferrin receptor (sTfR) in human serum has been known for quite a long time (4) and its concentration is accepted as diagnostic marker for erythropoietic activity (5, 6), little is known about the molecular basis of the shedding process, in particular the nature of the shedding protease involved. In diseases accompanied by enhanced erythropoiesis or TfR expression, like iron deficiency anemia, increased serum sTfR levels are observed (7-10), whereas lower levels of serum sTfR were determined in patients with aplastic anemia (8). The sTfR level remains unchanged in anemia arising from chronic disease, so that it is a reliable marker to distinguish iron deficiency anemia from the anemia of chronic inflammation and liver disease (11). It was shown that a human red blood cell fraction does not have an own TfR-specific proteolytic activity, whereas a white blood cell fraction doe...

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Section: The Transferrin Receptor (Tfr)mentioning

confidence: 99%

Shedding of the Transferrin Receptor Is Mediated Constitutively by an Integral Membrane Metalloprotease Sensitive to Tumor Necrosis Factor α Protease Inhibitor-2

Kaup¹,

Dassler²,

Weise³

et al. 2002

Journal of Biological Chemistry

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“…CPV and FPV both use the feline transferrin receptor (TfR) for the binding and infection of feline cells (54), and specific binding of CPV to the canine TfR is associated with the CPV infection of dogs and dog cells, since FPV does not bind that receptor (28). The TfR is a type II membrane protein which is expressed on the surface of cells as a homodimer (19). The structure of the human TfR ectodomain shows that each monomer is made up of a protease-like domain, an apical domain, and a helical domain which forms most of the dimer interface (8,35).…”

mentioning

confidence: 99%

“…The structure of the human TfR ectodomain shows that each monomer is made up of a protease-like domain, an apical domain, and a helical domain which forms most of the dimer interface (8,35). The TfR ectodomain is attached to a 32-residue stalk which holds the receptor about 30 Å above the plasma membrane (19), and the human TfR has a 28-residue transmembrane sequence and a 61-residue cytoplasmic domain (32). Tf binding is determined primarily by the TfR helical domain (9,21,87), while CPV and FPV binding to the feline or canine TfRs is controlled by interactions between the apical domain of the TfR and a raised region of the capsid surrounding the threefold axis of icosahedral symmetry (the threefold spike) (27,52).…”

mentioning

confidence: 99%

Parvovirus Infection of Cells by Using Variants of the Feline Transferrin Receptor Altering Clathrin-Mediated Endocytosis, Membrane Domain Localization, and Capsid-Binding Domains

Hueffer

Palermo

Parrish

2004

J Virol

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The feline and canine transferrin receptors (TfRs) bind canine parvovirus to host cells and mediate rapid capsid uptake and infection. The TfR and its ligand transferrin have well-described pathways of endocytosis and recycling. Here we tested several receptor-dependent steps in infection for their role in virus infection of cells. Deletions of cytoplasmic sequences or mutations of the Tyr-Thr-Arg-Phe internalization motif reduced the rate of receptor uptake from the cell surface, while polar residues introduced into the transmembrane sequence resulted in increased degradation of transferrin. However, the mutant receptors still mediated efficient virus infection. In contrast, replacing the cytoplasmic and transmembrane sequences of the feline TfR with those of the influenza virus neuraminidase (NA) resulted in a receptor that bound and endocytosed the capsid but did not mediate viral infection. This chimeric receptor became localized to detergent-insoluble membrane domains. To test the effect of structural virus receptor interaction on infection, two chimeric receptors were prepared which contained antibody-variable domains that bound the capsid in place of the TfR ectodomain. These chimeric receptors bound CPV capsids and mediated uptake but did not result in cell infection. Adding soluble feline TfR ectodomain to the virus during that uptake did not allow infection.

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“…A second possibility is that the self-association properties could be mediated through the extracellular domains. Recent studies with cryo-electron microscopy on the TR reconstituted in phospholipid vesicles indicate that the TR dimer consists of a large globular extracellular domain (6.4 ϫ 7.5 ϫ 10.5 nm) separated from the membrane by a thin molecular stalk (2.9 nm; Fuchs et al, 1998). Because the large extracellular domains of the dimer are tethered together through these closely associated stalks that traverse the membrane, it is conceivable that self-association occurs through the extracellular domains.…”

Section: Discussionmentioning

confidence: 99%

Down-Regulation of Cell Surface Receptors Is Modulated by Polar Residues within the Transmembrane Domain

Zaliauskiene

Kang

Brouillette³

et al. 2000

MBoC

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How recycling receptors are segregated from down-regulated receptors in the endosome is unknown.In previous studies, we demonstrated that substitutions in the transferrin receptor (TR) transmembrane domain (TM) convert the protein from an efficiently recycling receptor to one that is rapidly down regulated. In this study, we demonstrate that the "signal" within the TM necessary and sufficient for down-regulation is Thr 11 Gln 17 Thr 19 (numbering in TM). Transplantation of these polar residues into the wild-type TR promotes receptor down-regulation that can be demonstrated by changes in protein half-life and in receptor recycling. Surprisingly, this modification dramatically increases the TR internalization rate as well (ϳ79% increase). Sucrose gradient centrifugation and cross-linking studies reveal that propensity of the receptors to self-associate correlates with downregulation. Interestingly, a number of cell surface proteins that contain TM polar residues are known to be efficiently down-regulated, whereas recycling receptors for low-density lipoprotein and transferrin conspicuously lack these residues. Our data, therefore, suggest a simple model in which specific residues within the TM sequences dramatically influence the fate of membrane proteins after endocytosis, providing an alternative signal for down-regulation of receptor complexes to the wellcharacterized cytoplasmic tail targeting signals.

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Structural model of phospholipid-reconstituted human transferrin receptor derived by electron microscopy

Cited by 58 publications

References 43 publications

Shedding of the Transferrin Receptor Is Mediated Constitutively by an Integral Membrane Metalloprotease Sensitive to Tumor Necrosis Factor α Protease Inhibitor-2

Shedding of the Transferrin Receptor Is Mediated Constitutively by an Integral Membrane Metalloprotease Sensitive to Tumor Necrosis Factor α Protease Inhibitor-2

Parvovirus Infection of Cells by Using Variants of the Feline Transferrin Receptor Altering Clathrin-Mediated Endocytosis, Membrane Domain Localization, and Capsid-Binding Domains

Down-Regulation of Cell Surface Receptors Is Modulated by Polar Residues within the Transmembrane Domain

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