biology

Prelamin-A/C

Prelamin-A/C 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 Prelamin-A/C rather than just read about it. In short: Prelamin-A/C, or lamin A/C is a protein that in humans is encoded by the LMNA gene. Lamin A/C belongs to the lamin family of proteins.

Key takeaways

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

Reference excerpt

Prelamin-A/C, or lamin A/C is a protein that in humans is encoded by the LMNA gene. Lamin A/C belongs to the lamin family of proteins.

Function

In the setting of ZMPSTE24 deficiency, the final step of lamin processing does not occur, resulting in an accumulation of farnesyl-prelamin A. In Hutchinson–Gilford progeria syndrome, a 50-amino acid deletion in prelamin A (amino acids 607–656) removes the site for the second endoproteolytic cleavage. Consequently, no mature lamin A is formed, and a farnesylated mutant prelamin A (progerin) accumulates in cells. The nuclear lamina consist of a two-dimensional matrix of proteins located next to the inner nuclear membrane. The lamin family of proteins make up the matrix and are highly conserved in evolution. During mitosis, the lamina matrix is reversibly disassembled as the lamin proteins are phosphorylated. Lamin proteins are thought to be involved in nuclear stability, chromatin structure and gene expression. Vertebrate lamins consist of two types, A and B. Through alternate splicing, this gene encodes three type A lamin isoforms. Early in mitosis, maturation promoting factor (abbreviated MPF, also called mitosis-promoting factor or M-phase-promoting factor) phosphorylates specific serine residues in all three nuclear lamins, causing depolymerization of the lamin intermediate filaments. The phosphorylated lamin B dimers remain associated with the nuclear membrane via their isoprenyl anchor. Lamin A is targeted to the nuclear membrane by an isoprenyl group but it is cleaved shortly after arriving at the membrane. It stays associated with the membrane through protein-protein interactions of itself and other membrane associated proteins, such as TOR1AIP1 (LAP1). Depolymerization of the nuclear lamins leads to disintegration of the nuclear envelope. Transfection experiments demonstrate that phosphorylation of human lamin A is required for lamin depolymerization, and thus for disassembly of the nuclear envelope, which normally occurs early in mitosis.

Clinical significance

Mutations in the LMNA gene are associated with several diseases, including Emery–Dreifuss muscular dystrophy, familial partial lipodystrophy, limb girdle muscular dystrophy, dilated cardiomyopathy, Charcot–Marie–Tooth disease, and restrictive dermopathy. A truncated version of lamin A, commonly known as progerin, causes Hutchinson-Gilford-Progeria syndrome. To date over 1,400 SNPs are known. They can manifest in changes on mRNA, splicing or protein (e.g. Arg471Cys, Arg482Gln, Arg527Leu, Arg527Cys, Ala529Val) level.

DNA damage DNA double-strand damages can be repaired by either homologous recombination (HR) or non-homologous end joining (NHEJ). LMNA promotes genetic stability by maintaining the levels of proteins that have key roles in HR and NHEJ. Mouse cells that are deficient for maturation of prelamin A have increased DNA damage and chromosome aberrations, and show increased sensitivity to DNA damaging agents. In progeria, the inadequacy of DNA repair, due to defective LMNA, may cause features of premature aging (see DNA damage theory of aging).

Interactions LMNA has been shown to interact with:

References

Illustrations

Worked examples

Example 1 — a first encounter with Prelamin-A/C

Start with the simplest possible case. Write down what Prelamin-A/C 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 Prelamin-A/C 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 Prelamin-A/C 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 Prelamin-A/C

In research: Prelamin-A/C 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 Prelamin-A/C 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: Prelamin-A/C is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aging-related genes, Aging-related proteins, Genes on human chromosome 1, so understanding it makes those chapters shorter.
In everyday life: Look for Prelamin-A/C 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Prelamin-A/C” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Prelamin-A/C in 20 minutes

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

Frequently asked questions

What is Prelamin-A/C in simple terms?

Prelamin-A/C, or lamin A/C is a protein that in humans is encoded by the LMNA gene. Lamin A/C belongs to the lamin family of proteins.

Why does Prelamin-A/C 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 Prelamin-A/C?

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 Prelamin-A/C.