scholarly journals Combined radiolabel-binding and immunocytochemical evaluation of receptor–ligand interactions. Studies of transferrin receptors on activated lymphocytes

1981 ◽  
Vol 200 (1) ◽  
pp. 173-176 ◽  
Author(s):  
Gillian M. P. Galbraith ◽  
Robert M. Galbraith
Keyword(s):  
Transferrin Receptor ◽  
Transferrin Receptors ◽  
Receptor Ligand ◽  
Activated Lymphocytes ◽  
Sources Of Error ◽  
Composite Approach ◽  
Receptor Interactions ◽  
Potential Sources ◽  
Ligand Interactions

A protocol that involved both immunohistological and radiolabel-binding procedures was devised for the study of transferrin–receptor interactions. This composite approach yielded considerably more information than did either technique used alone, and also provided a simple means for exclusion of several common potential sources of error.

scholarly journals Local clustering of transferrin receptors promotes clathrin-coated pit initiation

2010 ◽  
Vol 191 (7) ◽  
pp. 1381-1393 ◽  
Author(s):  
Allen P. Liu ◽  
François Aguet ◽  
Gaudenz Danuser ◽  
Sandra L. Schmid
Keyword(s):  
Transferrin Receptor ◽  
Transferrin Receptors ◽  
Coated Pits ◽  
Major Pathway ◽  
Receptor Ligand ◽  
Local Clustering ◽  
Pit Initiation

Clathrin-mediated endocytosis (CME) is the major pathway for concentrative uptake of receptors and receptor–ligand complexes (cargo). Although constitutively internalized cargos are known to accumulate into maturing clathrin-coated pits (CCPs), whether and how cargo recruitment affects the initiation and maturation of CCPs is not fully understood. Previous studies have addressed these issues by analyzing the global effects of receptor overexpression on CME or CCP dynamics. Here, we exploit a refined approach using expression of a biotinylated transferrin receptor (bTfnR) and controlling its local clustering using mono- or multivalent streptavidin. We show that local clustering of bTfnR increased CCP initiation. By tracking cargo loading in individual CCPs, we found that bTfnR clustering preceded clathrin assembly and confirmed that bTfnR-containing CCPs mature more efficiently than bTfnR-free CCPs. Although neither the clustering nor the related changes in cargo loading altered the rate of CCP maturation, bTfnR-containing CCPs exhibited significantly longer lifetimes than other CCPs within the same cell. Together these results demonstrate that cargo composition is a key source of the differential dynamics of CCPs.

scholarly journals Highly efficient intercellular spreading of protein misfolding mediated by viral ligand-receptor interactions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shu Liu ◽  
André Hossinger ◽  
Stefanie-Elisabeth Heumüller ◽  
Annika Hornberger ◽  
Oleksandra Buravlova ◽  
...  
Keyword(s):  
Protein Misfolding ◽  
Viral Infections ◽  
Seed Transmission ◽  
Cell Contact ◽  
Receptor Ligand ◽  
Cellular Models ◽  
Receptor Interactions ◽  
Ligand Interactions ◽  
Direct Cell ◽  
Vesicular Stomatitis

AbstractProtein aggregates associated with neurodegenerative diseases have the ability to transmit to unaffected cells, thereby templating their own aberrant conformation onto soluble homotypic proteins. Proteopathic seeds can be released into the extracellular space, secreted in association with extracellular vesicles (EV) or exchanged by direct cell-to-cell contact. The extent to which each of these pathways contribute to the prion-like spreading of protein misfolding is unclear. Exchange of cellular cargo by both direct cell contact or via EV depends on receptor-ligand interactions. We hypothesized that enabling these interactions through viral ligands enhances intercellular proteopathic seed transmission. Using different cellular models propagating prions or pathogenic Tau aggregates, we demonstrate that vesicular stomatitis virus glycoprotein and SARS-CoV-2 spike S increase aggregate induction by cell contact or ligand-decorated EV. Thus, receptor-ligand interactions are important determinants of intercellular aggregate dissemination. Our data raise the possibility that viral infections contribute to proteopathic seed spreading by facilitating intercellular cargo transfer.

Modulation of Platelet Activation by Native DNA – Initial Description of Platelet Receptor Type, Number and Discrimination for Native DNA

1981 ◽  
Vol 45 (03) ◽  
pp. 263-266 ◽  
Author(s):  
B A Fiedel ◽  
M E Frenzke
Keyword(s):  
Platelet Aggregation ◽  
Human Platelets ◽  
Scatchard Analysis ◽  
Type Number ◽  
Single Class ◽  
Receptor Ligand ◽  
Platelet Receptor ◽  
Platelet Binding ◽  
Ligand Interactions ◽  
Initial Description

SummaryNative DNA (dsDNA) induces the aggregation of isolated human platelets. Using isotopically labeled dsDNA (125I-dsDNA) and Scatchard analysis, a single class of platelet receptor was detected with a KD = 190 pM and numbering ~275/platelet. This receptor was discriminatory in that heat denatured dsDNA, poly A, poly C, poly C · I and poly C · poly I failed to substantially inhibit either the platelet binding of, or platelet aggregation induced by, dsDNA; by themselves, these polynucleotides were ineffective as platelet agonists. However, poly G, poly I and poly G · I effectively and competitively inhibited platelet binding of the radioligand, independently activated the platelet and when used at a sub-activating concentration decreased the extent of dsDNA stimulated platelet aggregation. These data depict a receptor on human platelets for dsDNA and perhaps certain additional polynucleotides and relate receptor-ligand interactions to a physiologic platelet function.

scholarly journals Transcriptional regulation by iron of the gene for the transferrin receptor.

1986 ◽  
Vol 6 (1) ◽  
pp. 236-240 ◽  
Author(s):  
K Rao ◽  
J B Harford ◽  
T Rouault ◽  
A McClelland ◽  
F H Ruddle ◽  
...  
Keyword(s):  
Transferrin Receptor ◽  
K562 Cells ◽  
Iron Chelator ◽  
Transcriptional Level ◽  
Transferrin Receptors ◽  
Intracellular Iron ◽  
Human Transferrin Receptor ◽  
Diferric Transferrin ◽  
Permeable Iron

Treatment of K562 cells with desferrioxamine, a permeable iron chelator, led to an increase in the number of transferrin receptors. Increasing intracellular iron levels by treatment of cells with either human diferric transferrin or hemin lowered the level of the transferrin receptors. By using a cDNA clone of the human transferrin receptor, we showed that the changes in the levels of the receptor by iron were accompanied by alterations in the levels of the mRNA for the receptor. The rapidity of these changes indicated that the mRNA had a very short half-life. By using an in vitro transcriptional assay with isolated nuclei, we obtained evidence that this regulation occurred at the transcriptional level.

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