biology

Muskelin

Muskelin 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 Muskelin rather than just read about it. In short: Muskelin is a protein that in humans is encoded by the MKLN1 gene. Gene In humans, the MKLN1 gene is located on the long arm of chromosome 7 (7q32.3).

Key takeaways

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

Reference excerpt

Muskelin is a protein that in humans is encoded by the MKLN1 gene.

Gene In humans, the MKLN1 gene is located on the long arm of chromosome 7 (7q32.3). It produces 12 splice variant transcripts, 6 of which are translated into a protein product. It is widely expressed across human tissues.

Protein At its N-terminus, muskelin has a disicoidin domain. This is followed by the alpha helical domains Lis1 Homology (LisH) and C-terminal to LisH (CTLH). After these lies the kelch repeat β-propellor domain, followed at the C-terminus by the CRA domain. Muskelin acts as a scaffold in the C-terminal to LisH (CTLH) E3 ligase complex. It is one of two proteins, along with WDR26, that can facilitate the formation of a massive supramolecular structure (600 kDa).

CTLH complex Muskelin is a component of the CTLH complex, which assembles into distinct supramolecular structures depending on whether WDR26 or muskelin acts as the β-propeller subunit. The CTLH complex is a recently characterized RING E3 ubiquitin ligase. As an E3 ligase, it catalyzes the final step of the ubiquitination cascade by mediating the interaction between a ubiquitin-conjugating enzyme (E2) and the substrate protein targeted for ubiquitination. The CTLH complex primarily functions within the ubiquitin-proteasome system, tagging proteins for degradation by the 26S proteasome. The complex consists of several core components. Its structural scaffold is formed by RanBPM, GID8, and ARMC8. The RING heterodimer, composed of RMND5A and MAEA, is responsible for the complex’s E3 ligase activity by directly interacting with the E2 enzyme. GID4 functions as the primary substrate receptor, recognizing and recruiting proteins targeted for ubiquitination. WDR26 and muskelin act in a mutually exclusive manner to promote the assembly of a higher-order CTLH structure, which includes four scaffold units, two RING heterodimers, and two GID4 receptors. WDR26 achieves this through binding as a pair of homodimers, while muskelin binds as a pair of homotetramers, each inserting between scaffold units to stabilize the supramolecular structure. These WDR26- and muskelin-containing complexes are functionally distinct due to differences in their substrate-binding interfaces. This structural variation enables them to recruit different sets of substrates. In muskelin knockout cells, expression levels of 39 proteins are altered, 16 of which are also affected by WDR26 knockout, indicating 23 proteins are specifically regulated by the muskelin-containing CTLH complex. The muskelin-containing complex also regulates its own activity via a negative feedback mechanism. It has been shown to ubiquitinate and promote the degradation of muskelin itself, a process not observed with WDR26 or other subunits. This autoregulation substitutes for alternative substrate receptors, helping maintain appropriate substrate levels. Through its two distinct configurations, the CTLH complex participates in a wide range of cellular processes, including metabolism, cell proliferation and survival, the maternal to zygotic transition, cell migration and adhesion, immune responses, autophagy, and erythropoiesis. Accordingly, muskelin is broadly expressed across diverse tissues and cell types.

Species distribution The CTLH complex was first discovered in Saccharomyces cerevisiae (Brewer's yeast), however here it lacks a muskelin homologue. Similarly, it also lacks a muskelin homologue in plants and nematodes, however it does exist in higher order animals such as mammals, fish and amphibians.

Clinical significance The CTLH complex is mostly implicated in neurological conditions. The most well understood of these is Skraban–Deardorff syndrome, a neurodevelopmental disorder caused by a multitude of WDR26 mutations impairing its ability to form the supramolecular structure. A particular muskelin SNP has been linked with early-onset bipolar disorder via a genome-wide association study, however the biological mechanism for this is unclear.

References

Illustrations

Worked examples

Example 1 — a first encounter with Muskelin

Start with the simplest possible case. Write down what Muskelin 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 Muskelin 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 Muskelin 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 Muskelin

In research: Muskelin 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 Muskelin 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: Muskelin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 7, Human chromosome 7 gene stubs, Kelch proteins, so understanding it makes those chapters shorter.
In everyday life: Look for Muskelin 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 Muskelin in 20 minutes

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

Frequently asked questions

What is Muskelin in simple terms?

Muskelin is a protein that in humans is encoded by the MKLN1 gene. Gene In humans, the MKLN1 gene is located on the long arm of chromosome 7 (7q32.3).

Why does Muskelin 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 Muskelin?

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 Muskelin.