biology

Insulin-like growth factor 2 receptor

Insulin-like growth factor 2 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 Insulin-like growth factor 2 receptor rather than just read about it. In short: Insulin-like growth factor 2 receptor (IGF2R), also called the cation-independent mannose-6-phosphate receptor (CI-MPR) is a protein that in humans is encoded by the IGF2R gene. IGF2R is a multifunctional protein receptor that binds insulin-like growth factor 2 (IGF2) at the cell surface and mannose-6-phosphate (M6P)-tagged proteins in the trans-Golgi network.

Key takeaways

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Connect Insulin-like growth factor 2 receptor to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Insulin-like growth factor 2 receptor from memory before moving on to harder problems.

Reference excerpt

Insulin-like growth factor 2 receptor (IGF2R), also called the cation-independent mannose-6-phosphate receptor (CI-MPR) is a protein that in humans is encoded by the IGF2R gene. IGF2R is a multifunctional protein receptor that binds insulin-like growth factor 2 (IGF2) at the cell surface and mannose-6-phosphate (M6P)-tagged proteins in the trans-Golgi network.

Structure The structure of the IGF2R is a type I transmembrane protein (that is, it has a single transmembrane domain with its C-terminus on the cytoplasmic side of lipid membranes) with a large extracellular/lumenal domain and a relatively short cytoplasmic tail. The extracellular domain consists of a small region homologous to the collagen-binding domain of fibronectin and of fifteen repeats of approximately 147 amino acid residues. Each of these repeats is homologous to the 157-residue extracytoplasmic domain of the mannose 6-phosphate receptor. Binding to IGF2 is mediated through one of the repeats, while two different repeats are responsible for binding to mannose-6-phosphate. The IGF2R is approximately 300 kDa in size; it appears to exist and function as a dimer.

Function IGF2R functions to clear IGF2 from the cell surface to attenuate signalling, and to transport lysosomal acid hydrolase precursors from the Golgi apparatus to the lysosome. After binding IGF2 at the cell surface, IGF2Rs accumulate in forming clathrin-coated vesicles and are internalized. In the lumen of the trans-Golgi network, the IGF2R binds M6P-tagged cargo. The IGF2Rs (bound to their cargo) are recognized by the GGA family of clathrin adaptor proteins and accumulate in forming clathrin-coated vesicles. IGF2Rs from both the cell surface and the Golgi are trafficked to the early endosome where, in the relatively low pH environment of the endosome, the IGF2Rs release their cargo. The IGF2Rs are recycled back to the Golgi by the retromer complex, again by way of interaction with GGAs and vesicles. The cargo proteins are then trafficked to the lysosome via the late endosome independently of the IGF2Rs.

Interactions Insulin-like growth factor 2 receptor has been shown to interact with M6PRBP1.

Evolution The insulin-like growth factor 2 receptor function evolved from the cation-independent mannose 6-phosphate receptor and is first seen in Monotremes. The IGF-2 binding site was likely acquired fortuitously with the generation of an exonic splice site enhancer cluster in exon 34, presumably necessitated by several kilobases of repeat element insertions in the preceding intron. A six-fold affinity maturation then followed during therian evolution, coincident with the onset of imprinting and consistent with the theory of parental conflict.

See also Cluster of differentiation IGF-1 Receptor Mannose 6-phosphate receptor

References

Illustrations

Worked examples

Example 1 — a first encounter with Insulin-like growth factor 2 receptor

Start with the simplest possible case. Write down what Insulin-like growth factor 2 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 Insulin-like growth factor 2 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 Insulin-like growth factor 2 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 Insulin-like growth factor 2 receptor

In research: Insulin-like growth factor 2 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 Insulin-like growth factor 2 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: Insulin-like growth factor 2 receptor is common in secondary-school and first-year university syllabi. It links to neighbouring topics Clusters of differentiation, Genes on human chromosome 6, Receptors, so understanding it makes those chapters shorter.
In everyday life: Look for Insulin-like growth factor 2 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 Insulin-like growth factor 2 receptor in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Insulin-like growth factor 2 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 Insulin-like growth factor 2 receptor in simple terms?

Why does Insulin-like growth factor 2 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 Insulin-like growth factor 2 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 Insulin-like growth factor 2 receptor.