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Ubiquitin-binding domain

Ubiquitin-binding 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 Ubiquitin-binding domain rather than just read about it. In short: Ubiquitin-binding domains (UBDs) are protein domains that recognise and bind non-covalently to ubiquitin through protein-protein interactions. As of 2019, a total of 29 types of UBDs had been identified in the human proteome.

Ubiquitin-binding domain — main illustration
Ubiquitin-binding domain — illustration

Key takeaways

  • Ubiquitin-binding 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 Ubiquitin-binding domain to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Ubiquitin-binding domain from memory before moving on to harder problems.

Reference excerpt

Ubiquitin-binding domains (UBDs) are protein domains that recognise and bind non-covalently to ubiquitin through protein-protein interactions. As of 2019, a total of 29 types of UBDs had been identified in the human proteome. Most UBDs bind to ubiquitin only weakly, with binding affinities in the low to mid μM range. Proteins containing UBDs are known as ubiquitin-binding proteins or sometimes as "ubiquitin receptors".

Structure Most UBDs are of small size (often less than 50 amino acids) and adopt many different protein folds from multiple fold classes, including all-alpha, all-beta, and alpha/beta folds. Many UBDs can be roughly classified into four broad categories: alpha-helical structures (in some cases as small as a single helix, as in the ubiquitin-interacting motif); zinc fingers; pleckstrin homology (PH) domains; and domains similar to those in ubiquitin-conjugating (also known as E2) enzymes. Other UBDs not fitting these categories can be SH3 domains, PFU domains, and other structures. Small helical structures are the most common, and examples include ubiquitin-associated domains (UBA), CUE domains, the ubiquitin-interacting motif (UIM), the motif interacting with ubiquitin (MIU), and the VHS protein domain.

Binding mechanism Many UBDs of the UBA family bind to ubiquitin via a hydrophobic patch centred on a particular isoleucine residue (the "Ile44 patch"), although binding to other surface patches has been observed, for example the "Ile36 patch". Zinc finger UBDs have a broader range of binding modes including interactions with polar residues. Because many UBDs have a common or overlapping ubiquitin interaction surface, their interactions are often mutually exclusive; due to steric clashes, more than one UBD cannot physically interact with the same Ile44-centered hydrophobic patch on a single ubiquitin molecule. Most UBDs described to date bind to monoubiquitin and thus do not show a linkage-preference for the differently linked ubiquitin chains. There are, however, a handful of known, linkage-specific UBDs, that can specifically differentiate between the eight different ubiquitin linkages. This is important as the different linkage types are thought to signal for different molecular processes and linkage-specific recognition of these chains ensures the appropriate cellular response.

References

Illustrations

Ubiquitin-binding domain: The NMR structure of a UBA domain, among the most common types of ubiquitin-binding domain, from the protein ubiquilin-1 (top, cyan) bound to ubiquitin (bottom, orange). Isoleucine 44, the center of a hydrophobic patch on the ubiquitin surface that interacts with a number of ubiquitin-binding domains, is highlighted in blue. Rendered from PDB: 2JY6​.[1]
The NMR structure of a UBA domain, among the most common types of ubiquitin-binding domain, from the protein ubiquilin-1 (top, cyan) bound to ubiquitin (bottom, orange). Isoleucine 44, the center of a hydrophobic patch on the ubiquitin surface that interacts with a number of ubiquitin-binding domains, is highlighted in blue. Rendered from PDB: 2JY6​.[1]

Worked examples

Example 1 — a first encounter with Ubiquitin-binding domain

Start with the simplest possible case. Write down what Ubiquitin-binding 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 Ubiquitin-binding 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 Ubiquitin-binding 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 Ubiquitin-binding domain

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

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

Frequently asked questions

What is Ubiquitin-binding domain in simple terms?

Ubiquitin-binding domains (UBDs) are protein domains that recognise and bind non-covalently to ubiquitin through protein-protein interactions. As of 2019, a total of 29 types of UBDs had been identified in the human proteome.

Why does Ubiquitin-binding 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 Ubiquitin-binding 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 Ubiquitin-binding domain.

Tags

  • Protein domains

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