biology

PMEL (gene)

PMEL (gene) 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 PMEL (gene) rather than just read about it. In short: Melanocyte protein PMEL also known as premelanosome protein (PMEL), silver locus protein homolog (SILV) or Glycoprotein 100 (gp100), is a protein that in humans is encoded by the PMEL gene. Its gene product may be referred to as PMEL, silver, ME20, gp100 or Pmel17.

Key takeaways

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

Reference excerpt

Melanocyte protein PMEL also known as premelanosome protein (PMEL), silver locus protein homolog (SILV) or Glycoprotein 100 (gp100), is a protein that in humans is encoded by the PMEL gene. Its gene product may be referred to as PMEL, silver, ME20, gp100 or Pmel17.

Structure MEL is a type I transmembrane glycoprotein that is expressed primarily in melanosomes, which are the melanin-producing organelles in melanocytes of pigment cells of the skin and eye, and in most malignant melanomas. It is 661 amino acids long, with a mass of 100 kDa. The transmembrane form of PMEL is modified in the secretory pathway by elaboration of N-linked oligosaccharides and addition and modification of O-linked oligosaccharides. It is then targeted to precursors of the pigment organelle, the melanosome, where it is proteolytically processed to several small fragments. Some of these fragments form non-pathological amyloid that assemble into sheets and form the striated pattern that underlies melanosomal ultrastructure. PMEL cleavage is mediated by several proteases including a proprotein convertase of the furin family, a "sheddase" that might include members of the a disintegrin and metalloproteinase (ADAM) family, and additional proteases in melanosomes or their precursors. After the amyloidogenic region is cleaved, the small remaining integral membrane fragment is digested by γ-secretase.

Function This protein is involved in melanosome maturation, including melanogenesis, melanosome biogenesis, and melanin polymerization. The expression of the PMEL gene is regulated by the microphthalmia-associated transcription factor (MITF).

Clinical significance The gp100 protein is a melanoma antigen, i.e. a tumor-associated antigen. The gp100 protein contains differentiation antigens and has been widely studied as a target for melanoma immunotherapy. Different sequences of the GP100 peptide could be used for immunization against tumors. According to a case study, modifications of GP100, such as GP100-209 and GP100-208, have shown a greater number of antigen-specific CTL's (cytotoxic T lymphocytes), which can target and kill cancer cells. Short fragments of PMEL have been used to develop the gp100 cancer vaccine which is or contains gp100:209-217(210M). Hydrophilic recombinant gp100 protein (HR-gp100) has been topically applied on human intact skin in vitro, and used as a vaccine in a mouse model. It was demonstrated that HR-gp100 permeates into human skin, and is processed and presented by human dendritic cells. In the mouse model, an HR-gp100-based vaccine triggered antigen-specific T cell responses, as shown by proliferation assays, ELISA and intracellular staining for IFN-γ.

References

Illustrations

Worked examples

Example 1 — a first encounter with PMEL (gene)

Start with the simplest possible case. Write down what PMEL (gene) 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 PMEL (gene) 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 PMEL (gene) 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 PMEL (gene)

In research: PMEL (gene) 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 PMEL (gene) 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: PMEL (gene) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 12, Oncology, so understanding it makes those chapters shorter.
In everyday life: Look for PMEL (gene) 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 PMEL (gene) in 20 minutes

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

Frequently asked questions

What is PMEL (gene) in simple terms?

Why does PMEL (gene) 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 PMEL (gene)?

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 PMEL (gene).