Very low-density lipoprotein

Very low-density lipoprotein

Very low-density lipoprotein (VLDL) is a type of lipoprotein made by the liver. VLDL is one of the five major groups of lipoproteins (chylomicrons, VLDL, IDL, LDL, HDL) which enable fats and cholesterol to move within the water based solution of the blood stream. It is assembled in the liver from cholesterol and apolipoproteins. It is converted in the bloodstream to low-density lipoprotein (LDL). VLDL particles have a diameter of 30-80 nm. VLDL transports endogenous products where chylomicrons transport exogenous (dietary) products.

Function

VLDL transports endogenous triglycerides, phospholipids, cholesterol and cholesteryl esters. It functions as the body's internal transport mechanism for lipids.

Changes during circulation

Nascent VLDL circulates in blood and picks up apolipoprotein C-II and apolipoprotein E donated from High-Density Lipoprotein (HDL). At this point, the nascent VLDL becomes a mature VLDL. Once in circulation, the VLDL will come in contact with lipoprotein lipase (LPL) in the capillary beds in the body (adipose, cardiac, and skeletal muscle). The LPL will remove triglycerides from the VLDL for storage or energy production.

The VLDL now meets back up with HDL where apoC-II is transferred back to the HDL (but keeps apoE). In addition to this, the HDL transfers cholesteryl esters to the VLDL in exchange for phospholipids and triglycerides (via cholesteryl ester transfer protein).

As more and more triglycerides are removed from the VLDL because of the action of the LPL enzyme, the composition of the molecule changes, and it becomes intermediate density lipoprotein (IDL).

50% of IDL are recognized by receptors in the liver cells (because of the apoB-100 and apoE they contain) and are endocytosed.

The other 50% of IDL lose their apoE. When their cholesterol content becomes greater than the triglyceride content, they become low-density lipoprotein (LDL), with the primary apolipoprotein being apoB-100. The LDL is taken into a cell via the LDL receptor (endocytosis) where the contents are either stored, used for cell membrane structure, or converted into other products (steroid hormones or bile acids).

VLDL and disease

VLDL levels have been correlated with accelerated rates of atherosclerosis, and are elevated in a number of diseases and metabolic states.

The uniqueness of this correlation is disputed by Harchaoui and Boekholdt http://www.medscape.com/viewarticle/551425

ee also

* Combined hyperlipidemia


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Very low density lipoprotein — (VLDL) ist ein Bestandteil des Blutplasmas, und dient dem Transport von Triglyceriden, Cholesterin und Phospholipiden von der Leber zu den Geweben. Auf seinem Weg wandelt es sich durch Abgabe der Triglyceride von VLDL allmählich in LDL um. VLDLs… …   Deutsch Wikipedia

  • Very Low Density Lipoprotein — (VLDL) ist ein Bestandteil des Blutplasmas, und dient dem Transport von Triglyceriden, Cholesterin und Phospholipiden von der Leber zu den Geweben. Auf seinem Weg wandelt es sich durch die allmähliche Abgabe der Triglyceride von VLDL in LDL um.… …   Deutsch Wikipedia

  • very-low-density lipoprotein — ver ē n VLDL * * * (VLDL) a class of lipoproteins that transport triglycerides from the intestine and liver to adipose and muscle tissues. Synthesized by the liver, they contain primarily triglycerides in their lipid cores, with some cholesteryl… …   Medical dictionary

  • Very low density lipoprotein — Lipoprotéine de très basse densité Les VLDL (Very Low Density Lipoprotein, lipoprotéine de très basse densité) sont des lipoprotéines responsables du transfert des lipides endogènes de leur lieu de synthèse, le foie vers les tissus. Densité (par… …   Wikipédia en Français

  • Very low density lipoprotein receptor — [[Изображение:|px|Рецептор липопротеинов очень низкой плотности chemical structure]] very low density lipoprotein receptor Обозначения Symbol(s) VLDLR Entrez …   Википедия

  • very low-density lipoprotein — VLDL a lipoprotein that is the precursor of low density lipoprotein (LDL). Containing triglycerides and cholesterol, it is produced in the liver and circulates in the bloodstream, where its triglycerides are hydrolysed to free fatty acids by… …   The new mediacal dictionary

  • very low density lipoprotein — noun large lipoproteins rich in triglycerides; VLDLs circulate through the blood giving up their triglycerides to fat and muscle tissue until the VLDL remnants are modified and converted into LDL • Syn: ↑VLDL • Hypernyms: ↑lipoprotein …   Useful english dictionary

  • Low-density lipoprotein — (LDL) is a type of lipoprotein that transports cholesterol and triglycerides from the liver to peripheral tissues. LDL is one of the five major groups of lipoproteins; these groups include chylomicrons, very low density lipoprotein (VLDL),… …   Wikipedia

  • Low density lipoprotein receptor-related protein 8 — Low density lipoprotein receptor related protein 8, apolipoprotein e receptor, also known as LRP8, is a human gene.cite web | title = Entrez Gene: LRP8 low density lipoprotein receptor related protein 8, apolipoprotein e receptor| url =… …   Wikipedia

  • low-density lipoprotein — LDL a lipoprotein that is the principal form in which cholesterol is transported in the bloodstream: it accounts for approximately 70% of the circulating cholesterol in an individual. LDL is derived from very low density lipoprotein and is… …   The new mediacal dictionary

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”