biology

LAPTM4B

LAPTM4B 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 LAPTM4B rather than just read about it. In short: Lysosomal-associated transmembrane protein 4B is a protein that in humans is encoded by the LAPTM4B gene. LAPTM4B protein contains a lysosome localization motif and localizes on late endosomes and lysosomes.

Key takeaways

LAPTM4B belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LAPTM4B to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LAPTM4B from memory before moving on to harder problems.

Reference excerpt

Lysosomal-associated transmembrane protein 4B is a protein that in humans is encoded by the LAPTM4B gene. LAPTM4B protein contains a lysosome localization motif and localizes on late endosomes and lysosomes.

Clinical significance Increased expression of LAPTM4B has been found in breast, liver, lung, ovarian, uterine, gastric cancers. Elevated LAPTM4B level contributes to chemotherapy resistance in breast cancer. Overexpression of LAPTM4B causes anthracyclines (doxorubicin, daunorubicin, and epirubicin) resistance by retaining drug in the cytoplasm and decreasing nuclear localization of drug and drug induced DNA damage. LAPTM4B also promotes autophagy, a cell survival mechanism mediated by lysosomes. LAPTM4B promotes autophagy and renders tumor cells resistant to metabolic and genotoxic stress and results in more rapid tumor growth. Based on these findings, LAPTM4B can be utilized to be a therapeutic target to prevent chemotherapy resistance or a marker to identify the patients who will not benefit from anthracyclines. LAPTM4B mediates pro-cancer functions through epidermal growth factor receptor (EGFR), a well-known oncogene overexpressed and/or mutated in many solid tumors. In nutrient rich conditions, LAPTM4B amplifies EGFR signaling by blocking the intraluminal sorting and lysosomal degradation of activated EGFR. In stressed conditions such as nutrient deprivation, LAPTM4B alternatively sequesters inactive EGFR at an endosomal complex that contributes to autophagy upregulation, a function independent of EGFR tyrosine kinase activity. LAPTM4B selectively interacts with inactive EGFR, which is markedly promoted by serum starvation. Thus, LAPTM4B not only augments proliferative signaling, but it also increases cellular stress resistance. These studies suggest that co-targeting EGFR with LAPTM4B or autophagy might improve therapeutic response in EGFR positive cancer patients.

References

Illustrations

Worked examples

Example 1 — a first encounter with LAPTM4B

Start with the simplest possible case. Write down what LAPTM4B 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 LAPTM4B 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 LAPTM4B 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 LAPTM4B

In research: LAPTM4B 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 LAPTM4B 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: LAPTM4B is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 8, Protein stubs, so understanding it makes those chapters shorter.
In everyday life: Look for LAPTM4B 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 LAPTM4B in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LAPTM4B 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 LAPTM4B out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LAPTM4B in simple terms?

Why does LAPTM4B 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 LAPTM4B?

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 LAPTM4B.