Flow cytometric analysis of human peripheral blood mononuclear cells, untreated (left) or treated with anti-human CD3 (10 μg/ml, 72 hours, 37ºC) and anti-human CD28 (5 μg/ml, 72 hours, 37ºC) using CD71 (D7G9X) XP® Rabbit mAb (PE Conjugate) and co-stained with a CD3 antibody.
This Cell Signaling Technology antibody is conjugated to phycoerythrin (PE) and tested in-house for direct flow cytometry analysis in human cells. This antibody is expected to exhibit the same species cross-reactivity as the unconjugated CD71 (D7G9X) XP® Rabbit mAb #13113.
Supplied in PBS (pH 7.2), less than 0.1% sodium azide and 2 mg/ml BSA. Store at 4°C. Do not aliquot the antibodies. Protect from light. Do not freeze.
All reagents required for this protocol may be efficiently purchased together in our Intracellular Flow Cytometry Kit (Methanol) #13593, or individually using the catalog numbers listed below.
NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.
NOTE: When including fluorescent cellular dyes in your experiment (including viability dyes, DNA dyes, etc.), please refer to the dye product page for the recommended protocol. Visit www.cellsignal.com for a full listing of cellular dyes validated for use in flow cytometry.
NOTE: Adherent cells or tissue should be dissociated and in single-cell suspension prior to fixation.
NOTE: Optimal centrifugation conditions will vary depending upon cell type and reagent volume. Generally, 150-300g for 1-5 minutes will be sufficient to pellet the cells.
NOTE: If using whole blood, lyse red blood cells and wash by centrifugation prior to fixation.
NOTE: Antibodies targeting CD markers or other extracellular proteins may be added prior to fixation if the epitope is disrupted by formaldehyde and/or methanol. The antibodies will remain bound to the target of interest during the fixation and permeabilization process. However, note that some fluorophores (including PE and APC) are damaged by methanol and thus should not be added prior to permeabilization. Conduct a small-scale experiment if you are unsure.
NOTE: Count cells using a hemocytometer or alternative method.
posted July 2009
revised June 2020
Protocol Id: 407
CD71 (D7G9X) XP® Rabbit mAb (PE Conjugate) recognizes endogenous levels of total CD71 protein.
Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to residues surrounding Leu146 of human CD71 protein.
Transferrin receptor 1 (CD71, TFRC) is a type II transmembrane receptor and carrier protein responsible for the uptake of cellular iron through receptor-mediated endocytosis (1). Neutral pH at the cell surface promotes binding of the iron-binding glycoprotein transferrin (Tf) to the CD71 receptor. The receptor-ligand complex enters the cell through receptor-mediated endocytosis and is internalized into an endosome. Relatively lower endosomal pH leads to a change in the local charge environment surrounding the iron-transferrin binding site and results in the release of iron (2). The receptor-ligand complex is recycled to the cell surface where transferrin dissociates from the CD71 receptor (2). Ubiquitously expressed transferrin receptor is continuously recycled and undergoes clathrin-mediated endocytosis regardless of ligand binding state. The interaction between receptor and ligand has been studied in detail. The helical domain of CD71 directly interacts with the transferrin C-lobe and induces a conformation change in Tf to facilitate the transport process (3). Interaction between the receptor CD71 and transferrin is mediated by the membrane protein hemochromatosis (HFE). HFE binds the α-helical domain of CD71, blocking formation of the CD71-transferrin complex and inhibiting iron uptake (4,5). In addition to binding transferrin, CD71 also interacts with H-ferritin at the cell surface and transports this intracellular iron storage protein to cellular endosomes and lysosomes (6). Additional studies indicate that the transferrin receptor is an evolutionarily conserved receptor for a number or arenaviruses and at least one retrovirus (7,8). Aberrant expression of CD71 is seen in a number of cancers, including thyroid carcinomas, lymphomas, and T-lineage leukemias, suggesting a possible therapeutic role for targeted inhibition of the transferrin receptor (9,10).
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