biology

Ubiquitin carboxy-terminal hydrolase L1

Ubiquitin carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1 rather than just read about it. In short: Ubiquitin carboxy-terminal hydrolase L1 (EC 3.1.2.15, ubiquitin C-terminal hydrolase, UCH-L1) is a deubiquitinating enzyme. Function UCH-L1 is a member of a gene family whose products hydrolyze small C-terminal adducts of ubiquitin to generate the ubiquitin monomer.

Key takeaways

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Reference excerpt

Ubiquitin carboxy-terminal hydrolase L1 (EC 3.1.2.15, ubiquitin C-terminal hydrolase, UCH-L1) is a deubiquitinating enzyme.

Function UCH-L1 is a member of a gene family whose products hydrolyze small C-terminal adducts of ubiquitin to generate the ubiquitin monomer. Expression of UCH-L1 is highly specific to neurons and to cells of the diffuse neuroendocrine system and their tumors. It is abundantly present in all neurons (accounts for 1-2% of total brain protein), expressed specifically in neurons and testis/ovary. The catalytic triad of UCH-L1 contains a cysteine at position 90, an aspartate at position 176, and a histidine at position 161 that are responsible for its hydrolase activity.

Relevance to neurodegenerative disorders A point mutation (I93M) in the gene encoding this protein is implicated as the cause of Parkinson's disease in one German family, although this finding is controversial, as no other Parkinson's disease patients with this mutation have been found. Furthermore, a polymorphism (S18Y) in this gene has been found to be associated with a reduced risk for Parkinson's disease. This polymorphism has specifically been shown to have antioxidant activity. Another potentially protective function of UCH-L1 is its reported ability to stabilize monoubiquitin, an important component of the ubiquitin proteasome system. It is thought that by stabilizing the monomers of ubiquitin and thereby preventing their degradation, UCH-L1 increases the available pool of ubiquitin to be tagged onto proteins destined to be degraded by the proteasome. The gene is also associated with Alzheimer's disease, and required for normal synaptic and cognitive function. Loss of Uchl1 increases the susceptibility of pancreatic beta-cells to programmed cell death, indicating that this protein plays a protective role in neuroendocrine cells and illustrating a link between diabetes and neurodegenerative diseases. Patients with early-onset neurodegeneration in which the causative mutation was in the UCHL1 gene (specifically, the ubiquitin binding domain, E7A) display blindness, cerebellar ataxia, nystagmus, dorsal column dysfunction, and upper motor neuron dysfunction.

Ectopic expression Although UCH-L1 protein expression is specific to neurons and testis/ovary tissue, it has been found to be expressed in certain lung-tumor cell lines. This abnormal expression of UCH-L1 is implicated in cancer and has led to the designation of UCH-L1 as an oncogene. Furthermore, there is evidence that UCH-L1 might play a role in the pathogenesis of membranous glomerulonephritis as UCH-L1 de novo expression in podocytes was seen in PHN, the rat model of human mGN. This UCH-L1 expression is thought to induce at least in part podocyte hypertrophy.

Protein structure Human UCH-L1 and the closely related protein UCHL3 have one of the most complicated knot structure yet discovered for a protein, with five knot crossings. It is speculated that a knot structure may increase a protein's resistance to degradation in the proteasome. The conformation of the UCH-L1 protein may also be an important indication of neuroprotection or pathology. For example, the UCH-L1 dimer has been shown to exhibit the potentially pathogenic ligase activity and may lead to the aforementioned increase in aggregation of α-synuclein. The S18Y polymorphism of UCH-L1 has been shown to be less-prone to dimerization.

Interactions Ubiquitin carboxy-terminal hydrolase L1 has been shown to interact with COP9 constitutive photomorphogenic homolog subunit 5. UCH-L1 has also been shown to interact with α-synuclein, another protein implicated in the pathology of Parkinson disease. This activity is reported to be the result of its ubiquityl ligase activity which may be associated with the I93M pathogenic mutation in the gene. Most recently, UCH-L1 has been demonstrated to interact with the E3 ligase, parkin. Parkin has been demonstrated to bind and ubiquitinylate UCH-L1 to promote lysosomal degradation of UCH-L1.

See also Ubiquitin carboxyl-terminal esterase L3—the gene UCHL3 Alpha synuclein Parkinson disease Proteasome

References

Illustrations

Worked examples

Example 1 — a first encounter with Ubiquitin carboxy-terminal hydrolase L1

Start with the simplest possible case. Write down what Ubiquitin carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1

In research: Ubiquitin carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 3.1.2, Genes on human chromosome 4, Molecular neuroscience, so understanding it makes those chapters shorter.
In everyday life: Look for Ubiquitin carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1 in 20 minutes

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Frequently asked questions

What is Ubiquitin carboxy-terminal hydrolase L1 in simple terms?

Ubiquitin carboxy-terminal hydrolase L1 (EC 3.1.2.15, ubiquitin C-terminal hydrolase, UCH-L1) is a deubiquitinating enzyme. Function UCH-L1 is a member of a gene family whose products hydrolyze small C-terminal adducts of ubiquitin to generate the ubiquitin monomer.

Why does Ubiquitin carboxy-terminal hydrolase L1 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 carboxy-terminal hydrolase L1?

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 carboxy-terminal hydrolase L1.