Transferrin receptor
Encyclopedia
Transferrin receptor is a carrier protein
for transferrin
. It is needed for the import of iron into the cell and is regulated in response to intracellular iron concentration. It imports iron by internalizing the transferrin-iron complex through receptor-mediated endocytosis
.
TfR production in the cell is regulated according to iron levels by iron response/regulatory element binding protein (IRE-BP), also referred to as Iron Regulatory Protein (IRP). This protein binds to the hairpin like structure (IRE
) that is in the 3' UTR of the TfR receptor. Once binding occurs, degradation of mRNA of IRE is inhibited.
Carrier protein
Carrier proteins are proteins involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane. Carrier proteins are integral membrane proteins; that is they exist within and span the membrane across which they transport substances. The...
for transferrin
Transferrin
Transferrins are iron-binding blood plasma glycoproteins that control the level of free iron in biological fluids. In humans, it is encoded by the TF gene.Transferrin is a glycoprotein that binds iron very tightly but reversibly...
. It is needed for the import of iron into the cell and is regulated in response to intracellular iron concentration. It imports iron by internalizing the transferrin-iron complex through receptor-mediated endocytosis
Receptor-mediated endocytosis
Receptor-mediated endocytosis , also called clathrin-dependent endocytosis, is a process by which cells internalize molecules by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being internalized.-Process:After the binding of a...
.
Regulation
Low iron concentrations promote increased levels of transferrin receptor, to increase iron intake into the cell. Thus, transferrin receptor maintains cellular iron homeostasis.TfR production in the cell is regulated according to iron levels by iron response/regulatory element binding protein (IRE-BP), also referred to as Iron Regulatory Protein (IRP). This protein binds to the hairpin like structure (IRE
Iron response element
The Iron response element or Iron-responsive element is a short conserved stem-loop which is bound by iron response proteins . The IRE is found in UTRs of various mRNAs whose products are involved in iron metabolism. For example, the mRNA of ferritin contains one IRE in its 5' UTR...
) that is in the 3' UTR of the TfR receptor. Once binding occurs, degradation of mRNA of IRE is inhibited.