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Transferrin receptor

Transferrin receptor is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Transferrin receptor rather than just read about it. In short: Transferrin receptor (TfR) is a carrier protein for transferrin. It is needed for the import of iron into cells and is regulated in response to intracellular iron concentration.

Transferrin receptor — main illustration
Transferrin receptor — illustration

Key takeaways

  • Transferrin receptor belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Transferrin receptor to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Transferrin receptor from memory before moving on to harder problems.

Reference excerpt

Transferrin receptor (TfR) is a carrier protein for transferrin. It is needed for the import of iron into cells and is regulated in response to intracellular iron concentration. It imports iron by internalizing the transferrin-iron complex through receptor-mediated endocytosis. The existence of a receptor for transferrin iron uptake has been recognized since the late 1950s. Earlier two transferrin receptors in humans, transferrin receptor 1 and transferrin receptor 2 had been characterized and until recently cellular iron uptake was believed to occur chiefly via these two well documented transferrin receptors. Both these receptors are transmembrane glycoproteins. TfR1 is a high affinity ubiquitously expressed receptor while expression of TfR2 is restricted to certain cell types and is unaffected by intracellular iron concentrations. TfR2 binds to transferrin with a 25-30 fold lower affinity than TfR1. Although TfR1 mediated iron uptake is the major pathway for iron acquisition by most cells and especially developing erythrocytes, several studies have indicated that the uptake mechanism varies depending upon the cell type. It is also reported that Tf uptake exists independent of these TfRs although the mechanisms are not well characterized. The multifunctional glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) has been shown to utilize post translational modifications to exhibit higher order moonlighting behavior wherein it switches its function as a holo or apo transferrin receptor leading to either iron delivery or iron export respectively.

Post-transcriptional 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-responsive element-binding proteins, IRP1 and IRP2. In the absence of iron, one of these proteins (generally IRP2) binds to the hairpin like structure (IRE) that is in the 3' UTR of the TfR mRNA. Once binding occurs, the mRNA is stabilized and degradation is inhibited.

See also Transferrin receptor 1 Transferrin receptor 2 Soluble transferrin receptor GAPDH

References

Further reading

External links Transferrin+receptor at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Okam M (2001-01-29). "Iron Transport and Cellular Uptake". Information Center for Sickle Cell and Thalassemic Disorders. Brigham and Women's Hospital and Harvard Medical School. Retrieved 2010-12-19.

Illustrations

Transferrin receptor illustration

Worked examples

Example 1 — a first encounter with Transferrin receptor

Start with the simplest possible case. Write down what Transferrin receptor claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Transferrin receptor before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Transferrin receptor ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Transferrin receptor

In research
Transferrin receptor appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Transferrin receptor in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Transferrin receptor is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 3, Genes on human chromosome 7, Iron metabolism, so understanding it makes those chapters shorter.
In everyday life
Look for Transferrin receptor outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Transferrin receptor in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Transferrin receptor means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Transferrin receptor out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Transferrin receptor in simple terms?

Transferrin receptor (TfR) is a carrier protein for transferrin. It is needed for the import of iron into cells and is regulated in response to intracellular iron concentration.

Why does Transferrin receptor matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Transferrin receptor?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Transferrin receptor.

Tags

  • Genes on human chromosome 3
  • Genes on human chromosome 7
  • Iron metabolism
  • Transferrins

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