biology

IMD domain

IMD domain 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 IMD domain rather than just read about it. In short: In molecular biology, the IMD domain (IRSp53 and MIM (missing in metastases) homology Domain) or I-BAR domain (Inverse BAR domain) is a BAR-like domain of approximately 250 amino acids found at the N-terminus in the insulin receptor tyrosine kinase substrate p53 (IRSp53/BAIAP2) and in the evolutionarily related IRSp53/MIM (MTSS1) family. In IRSp53, a ubiquitous regulator of the actin cytoskeleton, the IMD domain act…

Key takeaways

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

Reference excerpt

In molecular biology, the IMD domain (IRSp53 and MIM (missing in metastases) homology Domain) or I-BAR domain (Inverse BAR domain) is a BAR-like domain of approximately 250 amino acids found at the N-terminus in the insulin receptor tyrosine kinase substrate p53 (IRSp53/BAIAP2) and in the evolutionarily related IRSp53/MIM (MTSS1) family. In IRSp53, a ubiquitous regulator of the actin cytoskeleton, the IMD domain acts as conserved F-actin bundling domain involved in filopodium formation. Filopodium-inducing IMD activity is regulated by Cdc42 and Rac1 (Rho-family GTPases) and is SH3-independent, and dependent on the membrane binding and deforming activity.

Family members The IRSp53/MIM family is a membrane deforming and novel F-actin bundling protein family that includes invertebrate relatives:

Vertebrate MIM (missing in metastasis) (MTSS1), an actin-binding scaffold protein that may be involved in cancer metastasis. Vertebrate ABBA-1 (MTSS1L), a MIM-related protein. Vertebrate brain-specific angiogenesis inhibitor 1-associated protein 2 (BAI1-associated protein 2) or insulin receptor tyrosine kinase substrate p53 (IRSp53), a multifunctional adaptor protein that links Rac1 with a Wiskott–Aldrich syndrome family verprolin-homologous protein 2 (WAVE2/WASF2) to induce lamellipodia or Cdc42 with Mena to induce filopodia. Vertebrate brain-specific angiogenesis inhibitor 1-associated protein 2-like proteins 1 and 2 (BAI1-associated protein 2-like proteins 1 and 2, BAIAP2L1 and BAIAP2L2). Drosophila melanogaster (Fruit fly) CG32082-PA. Caenorhabditis elegans M04F3.5 protein.

Subgroups The vertebrate IRSp53/MIM family is divided into two major groups: the IRSp53 subfamily and the MIM/ABBA subfamily. The putative invertebrate homologues are positioned between them. The IRSp53 subfamily members contain an SH3 domain, and the MIM/ABBA subfamily proteins contain a WH2 (WASP-homology 2) domain. The vertebrate SH3-containing subfamily is further divided into three groups according to the presence or absence of the WWB and the half-CRIB motif. The IMD domain can bind to and bundle actin filaments, bind to membranes and interact with the small GTPase Rac.

Structure The IMD domain folds as a coiled coil of three extended alpha-helices and a shorter C-terminal helix. Helix 4 packs tightly against the other three helices, and thus represents an integral part of the domain. The fold of the IMD domain closely resembles that of the BAR (Bin-Amphiphysin-RVS) domain, a functional module serving both as a sensor and inducer of membrane curvature that is compatible for plasma membrane protrusions including filopodia and spines. The IMD domain is also known as the I-BAR domain because of its inverse curvature of the membrane binding surface compared to that of the BAR domain. The WH2 domain performs a scaffolding function.

References

Illustrations

Worked examples

Example 1 — a first encounter with IMD domain

Start with the simplest possible case. Write down what IMD domain 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 IMD domain 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 IMD domain 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 IMD domain

In research: IMD domain 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 IMD domain 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: IMD domain is common in secondary-school and first-year university syllabi. It links to neighbouring topics Protein families, so understanding it makes those chapters shorter.
In everyday life: Look for IMD domain 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 IMD domain in 20 minutes

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

Frequently asked questions

What is IMD domain in simple terms?

Why does IMD domain 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 IMD domain?

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 IMD domain.