biology

Inositol trisphosphate receptor

Inositol trisphosphate 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 Inositol trisphosphate receptor rather than just read about it. In short: Inositol trisphosphate receptor (InsP3R, IP3R) is a membrane glycoprotein complex acting as a Ca2+ channel activated by inositol trisphosphate (InsP3, IP3). InsP3R is very diverse among organisms, and is necessary for the control of cellular and physiological processes including cell division, cell proliferation, apoptosis, fertilization, development, behavior, learning and memory.

Key takeaways

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

Reference excerpt

Inositol trisphosphate receptor (InsP3R, IP3R) is a membrane glycoprotein complex acting as a Ca2+ channel activated by inositol trisphosphate (InsP3, IP3). InsP3R is very diverse among organisms, and is necessary for the control of cellular and physiological processes including cell division, cell proliferation, apoptosis, fertilization, development, behavior, learning and memory. Inositol triphosphate receptor represents a dominant second messenger leading to the release of Ca2+ from intracellular store sites. There is strong evidence suggesting that the InsP3R plays an important role in the conversion of external stimuli to intracellular Ca2+ signals characterized by complex patterns relative to both space and time, such as Ca2+ waves and oscillations.

Discovery The InsP3 receptor was first purified from rat cerebellum by neuroscientists Surachai Supattapone and Solomon Snyder at Johns Hopkins School of Medicine. The cDNA of the InsP3 receptor was first cloned in the laboratory of Katsuhiko Mikoshiba. The initial sequencing was reported as an unknown protein enriched in the cerebellum called P400. The large size of this open reading frame indicated a molecular weight similar to the protein purified biochemically, and soon thereafter it was confirmed that the protein P400 was in fact the inositol trisphosphate receptor.

Distribution The receptor has a broad tissue distribution but is especially abundant in the cerebellum. Most of the InsP3Rs are found integrated into the endoplasmic reticulum.

Structure Using X-ray crystallography and cryo-electron microscopy (cryo-EM) several protein structures of IP3Rs were obtained from mouse, rat, and human. Those structures helped to define the overall architecture of the channel. The 1.2 MDa C4-symmetric assembly consists of an ER-embedded transmembrane domain (TMD) in a domain-swapped 6 transmembrane (6TM) cation channel fold that is capped by a large cytosolic domain (CD). In this manner, IP3Rs share significant homology with the much larger and distantly-related ryanodine receptors. The CD contains all known ligand binding sites, including the IP3 binding site, two Ca2+ binding sites, an adenine nucleotide binding site, and a C2H2 Zn2+ finger fold. A comprehensive Ca2+-dependent conformational landscape has been defined by cryo-EM.

See also Inositol Inositol phosphate Inositol monophosphate Inositol trisphosphate Inositol pentakisphosphate Inositol hexaphosphate MRVI1 associated through complex formation.

References

External links Inositol+Trisphosphate+Receptor at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Illustrations

Worked examples

Example 1 — a first encounter with Inositol trisphosphate receptor

Start with the simplest possible case. Write down what Inositol trisphosphate 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 Inositol trisphosphate 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 Inositol trisphosphate 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 Inositol trisphosphate receptor

In research: Inositol trisphosphate 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 Inositol trisphosphate 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: Inositol trisphosphate receptor is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 12, Genes on human chromosome 3, Genes on human chromosome 6, so understanding it makes those chapters shorter.
In everyday life: Look for Inositol trisphosphate 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 Inositol trisphosphate receptor in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Inositol trisphosphate 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.
Explain Inositol trisphosphate receptor out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Inositol trisphosphate receptor in simple terms?

Why does Inositol trisphosphate 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 Inositol trisphosphate 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 Inositol trisphosphate receptor.