biology

XCR1

XCR1 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 XCR1 rather than just read about it. In short: The "C" sub-family of chemokine receptors contains only one member: XCR1, the receptor for XCL1 and XCL2 (or lymphotactin-1 and -2). XCR1 is also known as GPR5.

Key takeaways

XCR1 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect XCR1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XCR1 from memory before moving on to harder problems.

Reference excerpt

The "C" sub-family of chemokine receptors contains only one member: XCR1, the receptor for XCL1 and XCL2 (or lymphotactin-1 and -2). XCR1 is also known as GPR5.

Function The protein encoded by this gene is a chemokine receptor belonging to the G protein-coupled receptor superfamily. The family members are characterized by the presence of 7 transmembrane domains and numerous conserved amino acids. This receptor is most closely related to RBS11 and the MIP1-alpha/RANTES receptor. It transduces a signal by increasing the intracellular calcium ions level. The viral macrophage inflammatory protein-II is an antagonist of this receptor and blocks signaling. Two alternatively spliced transcript variants encoding the same protein have been found for this gene. Cross-presenting dendritic cells (DCs) in the spleen develop into XCR1+ DCs in the small intestine, T cell zones of Peyer's patches, and T cell zones and sinuses of mesenteric lymph nodes. XCR1+ DCs specialize in cross-presentations of orally applied antigens. The integrin SIRPα is also a differentiating factor for the XCR1+ DCs. The development transcription factor Batf3 helps develop the differences between XCR1+ DCs and CD103+ CD11b- DCs. XCL1 contributes to chemotaxis only in CD8+ murine cells, but not other DC types, B cells, T cells, or NK cells. Only some of these CD8+ murine cells expressed XCR1 receptors. NK cells release XCL1 along with IFN-γ and some other chemokines upon encountering certain bacteria such as Listeria or MCMV. XCR1+ and CD8+cells work together to cross-present antigen and communicate CD8+ activation. Cross presentation of XCR1+ CD8+ and XCR1+ CD8- cells was strongest, as is expected since they have XCR1 receptors. CD4+ and CD8+ may become outdated terms, since the activity of the cell appears to be primarily dependent upon the expression of XCR1, which will make a population far more similar than the expression of CD4 or CD8. XCR1+ cells are dependent on the growth factor Ftl3 ligand and are nonexistent in Batf3- deficient mice. Also, XCR1+ DCs are related to CD103+CD11b- DCs. XCL1 is expressed by medullary thymic epithelial T cells (mTECs) while XCR1 is expressed by thymic dendritic cells (tDCs). This communication helps with the destruction of cells that are not self-tolerant. When mice lose the ability to express XCL1, they are deficient in accumulation of tDCs and producing naturally occurring regulatory T cells (nT reg cells). The displaying of XCL1 by mTECs, tDC chemotaxis, and nT reg cell production are all decreased in mice that lack Aire, demonstrating it as an important regulator of XCL1 production. Naive CD8+ T cells are prepared when tumors form by cross-presentation via XCR1+ DCs and as a result will require a lower threshold to respond to antigen. Memory CD8+ T lymphocytes (mCTLs) are activated first after infection and then are signaled by CXCR3, IL-12, and CXCL9 by other XCR1+ DCs. In order to make a powerful secondary infection response, cytokine and chemokine signaling between XCR1+ DCs and NK cells must occur.

References

External links "Chemokine Receptors: XCR1". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2008-06-07. Retrieved 2008-12-04.

Illustrations

Worked examples

Example 1 — a first encounter with XCR1

Start with the simplest possible case. Write down what XCR1 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 XCR1 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 XCR1 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 XCR1

In research: XCR1 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 XCR1 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: XCR1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cytokines, Genes on human chromosome 3, Integral membrane proteins, so understanding it makes those chapters shorter.
In everyday life: Look for XCR1 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “XCR1” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study XCR1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XCR1 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain XCR1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XCR1 in simple terms?

The "C" sub-family of chemokine receptors contains only one member: XCR1, the receptor for XCL1 and XCL2 (or lymphotactin-1 and -2). XCR1 is also known as GPR5.

Why does XCR1 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 XCR1?

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 XCR1.