biology

Photoreceptor cell-specific nuclear receptor

Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear receptor rather than just read about it. In short: NR2E3 (nuclear receptor subfamily 2, group E, member 3), also known as photoreceptor cell-specific nuclear receptor (PNR), is a protein that in humans is encoded by the NR2E3 gene. PNR is a member of the nuclear receptor super family of intracellular transcription factors.

Key takeaways

Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear receptor to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Photoreceptor cell-specific nuclear receptor from memory before moving on to harder problems.

Reference excerpt

NR2E3 (nuclear receptor subfamily 2, group E, member 3), also known as photoreceptor cell-specific nuclear receptor (PNR), is a protein that in humans is encoded by the NR2E3 gene. PNR is a member of the nuclear receptor super family of intracellular transcription factors.

Function NR2E3 was initially cloned from human retinoblastoma Y79 cells and a mouse λZAP eye cDNA library in 1999. In addition to retinal photoreceptor cells, NR2E3 is expressed in many tissues such as the urogenital and respiratory systems in humans and mice, suggesting potential functions beyond the retina cells. The main target genes of PNR as a transcription factor are rhodopsin and several opsins which are essential for sight. Since 2011, NR2E3 has been implicated in tumorigenesis through activating p53 as a transcriptional cofactor. NR2E3 enhances p53 acetylation via forming a complex of NR2E3-p300-p53. NR2E3 mutants such as R76W and R97H, fail to activate p53. Interstingly, NR2E3 rescues the wild-type activity of many mutated p53, including R175H hot-spot gain-of-function mutation. Compound 11a, the agonist of NR2E3, has shown broad inhibitory effects on the cancer cells in NCI-60 cancer cell panel. 11a stimulates NR2E3-mediated p53 activation while also activating NR2E1 and NR2F2 in a less degree. The NR2E3-knock out mouse model suggests that NR2E3 may inhibit liver cancer growth.

Structure and ligands The crystal structure of PNR's ligand-binding domain is known. It self-dimerizes into, by default, a repressor state. Computer simulations based on this model shows that a ligand could possibly fit into PNR and switch it into a transcription activator. 13-cis retinoic acid is a known weak agonist that fits into such a pocket, but no physiologic ligand is known. Two synthetic compounds, 11A and 11B, appear to be agonists but do not go into the pocket and instead work as allosteric modulators. A more recent screening identifies another compound called photoregulin-1 (PR1) that functions as a reverse agonist, an activity possibly useful in the management of retinitis pigmentosa.

Clinical significance Mutations in the NR2E3 gene have been linked to several inherited retinal diseases, including enhanced S-cone syndrome (ESCS), a form of retinitis pigmentosa, and Goldmann-Favre syndrome. By analyzing TCGA database and "All of Us" database, high expression of NR2E3 is associated with superior prognosis of cancer including breast cancer. The mutation frequency of NR2E3 is higher in four types of cancer, such as colon cancer, than in the regular population.

References

Illustrations

Worked examples

Example 1 — a first encounter with Photoreceptor cell-specific nuclear receptor

Start with the simplest possible case. Write down what Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear receptor

In research: Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear 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: Photoreceptor cell-specific nuclear receptor is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 15, Human chromosome 15 gene stubs, Intracellular receptors, so understanding it makes those chapters shorter.
In everyday life: Look for Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear receptor in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Photoreceptor cell-specific nuclear receptor 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.
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Frequently asked questions

What is Photoreceptor cell-specific nuclear receptor in simple terms?

Why does Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear 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 Photoreceptor cell-specific nuclear receptor.