biology

Very low-density lipoprotein

Very low-density lipoprotein 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 Very low-density lipoprotein rather than just read about it. In short: Very-low-density lipoprotein (VLDL), density relative to extracellular water, is a type of lipoprotein made by the liver. VLDL is one of the five major groups of lipoproteins (chylomicrons, VLDL, intermediate-density lipoprotein, low-density lipoprotein, high-density lipoprotein) that enable fats and cholesterol to move within the water-based solution of the bloodstream.

Key takeaways

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

Reference excerpt

Very-low-density lipoprotein (VLDL), density relative to extracellular water, is a type of lipoprotein made by the liver. VLDL is one of the five major groups of lipoproteins (chylomicrons, VLDL, intermediate-density lipoprotein, low-density lipoprotein, high-density lipoprotein) that enable fats and cholesterol to move within the water-based solution of the bloodstream. VLDL is assembled in the liver from triglycerides, cholesterol, and apolipoproteins. VLDL is converted in the bloodstream to low-density lipoprotein (LDL) and intermediate-density lipoprotein (IDL). VLDL particles have a diameter of 30–80 nanometers (nm). VLDL transports endogenous products, whereas chylomicrons transport exogenous (dietary) products. In the early 2010s both the lipid composition and protein composition of this lipoprotein were characterised in great detail.

Physical properties Very-low-density lipoprotein size is variable, with diameters ranging from approximately 35 to 70 nm. Some researchers further classify VLDL particles into VLDL1 and VLDL2 based on size (as measured by Svedberg flotation units), where VLDL1 particles are larger and contain more triglycerides, while other researchers create a tripartite system by subdividing VLDL1 into larger VLDL1 and smaller VLDL2 and relabeling VLDL2 as VLDL3.

Function Very-low-density lipoproteins transport endogenous triglycerides, phospholipids, cholesterol, and cholesteryl esters. They function as the body's internal transport mechanism for lipids. In addition they can assist in long-range transport of hydrophobic intercellular messengers, like the morphogen Indian hedgehog (protein).

Changes during circulation Nascent VLDL released from the liver contains apolipoprotein B100, apolipoprotein C1 (apoC1), apolipoprotein E (apoE), cholesterol, cholesteryl esters, and triglycerides. As it circulates in blood, it picks up apolipoprotein C-II (apoC-II) and additional apoE donated from high-density lipoprotein (HDL). At this point, nascent VLDL becomes a mature VLDL. Once in circulation, VLDL will come in contact with lipoprotein lipase (LPL) in the capillary beds in the body (adipose, cardiac, and skeletal muscle). LPL will remove triglycerides from VLDL for storage or energy production. VLDL now meets back up with HDL where apoC-II is transferred back to HDL (but keeps apoE). HDL also transfers cholesteryl esters to the VLDL in exchange for phospholipids and triglycerides via cholesterylester transfer protein (CETP). As more and more triglycerides are removed from the VLDL because of the action of LPL and CETP enzymes, the composition of the molecule changes, and it becomes intermediate-density lipoprotein (IDL). Fifty percent of IDLs are recognized by receptors in the liver cells because of the apolipoprotein B-100 (apoB-100) and apoE they contain and are endocytosed. The other 50% of IDL lose apoE; when their cholesterol content becomes greater than the content of triglyceride, they become LDL, with apoB-100 as the primary apolipoprotein. The LDL is taken into a cell via the LDL receptor via endocytosis, where the contents are either stored, used for cell membrane structure, or converted into other products such as steroid hormones or bile acids.

See also Combined hyperlipidemia Lipid profile

Notes and references

Worked examples

Example 1 — a first encounter with Very low-density lipoprotein

Start with the simplest possible case. Write down what Very low-density lipoprotein 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 Very low-density lipoprotein 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 Very low-density lipoprotein 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 Very low-density lipoprotein

In research: Very low-density lipoprotein 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 Very low-density lipoprotein 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: Very low-density lipoprotein is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lipoproteins, so understanding it makes those chapters shorter.
In everyday life: Look for Very low-density lipoprotein 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 Very low-density lipoprotein in 20 minutes

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

Frequently asked questions

What is Very low-density lipoprotein in simple terms?

Why does Very low-density lipoprotein 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 Very low-density lipoprotein?

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 Very low-density lipoprotein.