Lipoproteins

Information about Lipoproteins

A lipoprotein is a biochemical assembly that contains both proteins and lipids. The lipids or their derivatives may be covalently or non-covalently bound to the proteins. Many enzymes, transporters, structural proteins, antigens, adhesins and toxins are lipoproteins. Examples include the high density and low density lipoproteins of the blood, the transmembrane proteins of the mitochondrion and the chloroplast, and bacterial lipoproteins [1].

Function

The lipids are often an essential part of the complex, even if they seem to have no catalytic activity themselves. To isolate transmembrane lipoproteins from their associated membranes, detergents are often needed.

All cells use and rely on fats and, for all animal cells, cholesterol as building blocks to create the multiple membranes which cells use to both control internal water content, internal water soluble elements and to organize their internal structure and protein enzymatic systems.

Lipoproteins in the blood, a water medium, carry fats around the body. The protein particles have charged groups aimed outward so as to attract water molecules; this makes them soluble in the salt water based blood pool. Triglyceride-fats and cholesterol are carried internally, shielded by the protein particle from the water.

The interaction of the proteins forming the surface of the particles with (a) enzymes in the blood, (b) with each other and (c) with specific proteins on the surfaces of cells determine whether triglycerides and cholesterol will be added to or removed from the lipoprotein transport particles.

Regarding atheroma development and progression vs. regression, the key issue has always been cholesterol transport patterns, not cholesterol concentration itself.

Classification

By density

General categories of lipoproteins, listed in order from larger and less dense (more fat than protein) to smaller and more dense (more protein, less fat):

Chylomicrons - carry triacylglycerol (fat) from the intestines to the liver and to adipose tissue.
Very low density lipoproteins - carry (newly synthesised) triacylglycerol from the liver to adipose tissue.
Intermediate density lipoproteins - are intermediate between VLDL and LDL. They are not usually detectable in the blood.
Low density lipoproteins - carry cholesterol from the liver to cells of the body. Sometimes referred to as the "bad cholesterol" lipoprotein.
High density lipoproteins - collects cholesterol from the body's tissues, and brings it back to the liver. Sometimes referred to as the "good cholesterol" lipoprotein.

Alpha and beta

It is also possible to classify lipoproteins as "alpha" and "beta", akin to the classification of proteins in serum protein electrophoresis. This terminolgy is sometimes used in describing lipid disorders such as Abetalipoproteinemia.

Lipoprotein(a)

Lipoprotein(a) - Lp(a), Cardiology diagnostic tests

Normal: <14mg/dL

High risk: >19mg/dL

How to lower: exercise, niacin, aspirin.

source: Beyond Cholesterol, Julius Torelli MD, 2005 ISBN 0-312-34863-0 p.91

External links

• • [ e] Lipids: membrane lipids
Lipid bilayer - Phospholipids - Proteolipids - Sphingolipids - Sterols

• • [ e] Lipids: lipoproteins
Chylomicron \| HDL \| LDL \| IDL \| VLDL \| Lp(a) Apolipoproteins: APOA1 \| APOA2 \| APOB \| APOC1 \| APOC2 \| APOC3 \| APOC4 \| APOD \| APOE \| APOH

Biochemistry is the study of the chemical processes in living organisms.^[1] The word "biochemistry" comes from the Greek word βιοχημεία biochēmeia, which means "the chemistry of life.
..... Click the link for more information.

Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
..... Click the link for more information.

Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing
..... Click the link for more information.

Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions.^[1] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.
..... Click the link for more information.

Transporter may refer to vehicles or transport:

transporter, a business or person involved in the transport of goods or people
transporter, a vehicle used to transport objects or material, especially a heavy hauler or related type of truck

..... Click the link for more information.

An antigen or immunogen is a molecule that stimulates an immune response. The word originated from the notion that they can stimulate antibody generation. We now know that the immune system does not only consist of antibodies.
..... Click the link for more information.

Adherence is often an essential step in bacterial pathogenesis or infection, required for colonizing a new host.^[1] To effectively adhere to host surfaces, many bacteria produce multiple adherence factors called adhesins.
..... Click the link for more information.

toxin (Greek: τοξικόν, toxikon, lit. (poison) for use on arrows) is a poisonous substance produced by living cells or organisms.
..... Click the link for more information.

Blood is a specialized biological fluid consisting of red blood cells (also called RBCs or erythrocytes), white blood cells (also called leukocytes) and platelets (also called thrombocytes) suspended in a complex fluid medium known as blood plasma.
..... Click the link for more information.

Cytochromes are generally membrane-bound hemoproteins that contain heme groups and carry out electron transport.

They are either found as monomeric proteins (i.e. cytochrome c) or as subunits of bigger enzymatic complexes that catalyze redox reactions.
..... Click the link for more information.

Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.

Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide to produce sugars, the raw material for energy and biomass production in all green plants
..... Click the link for more information.

Detergent is a compound, or a mixture of compounds, intended to assist cleaning. The term is often used to differentiate between soap and other chemical surfactants used for cleaning purposes.
..... Click the link for more information.

Fat

Fat may refer to:

Fat, a group of compounds that are generally soluble in organic solvents and largely insoluble in water
Adipose tissue, an anatomical term for loose connective tissue composed of adipocytes

..... Click the link for more information.

Editing of this page by unregistered or newly registered users is currently disabled until (UTC) due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or
..... Click the link for more information.

Cholesterol is a sterol (a combination steroid and alcohol), a lipid found in the cell membranes of all tissues, and is transported in the blood plasma of all animals. Because cholesterol is synthesized by all eukaryotes, trace amounts of cholesterol are also found in membranes of
..... Click the link for more information.

Atheroma
Classification & external resources

ICD-10 I 70.9
ICD-9 440

DiseasesDB 1039

MeSH C14.907.137.126.307 In pathology, an atheroma
..... Click the link for more information.

Chylomicrons are large lipoprotein particles (having a diameter of 75 to 1,200nm) that are created by the absorptive cells of the small intestine.The chylomicrons are released by exocytosis from enterocytes into lacteals, lymphatic vessels originating in the villi of the small
..... Click the link for more information.

Triglyceride (help info ) (more properly known as triacylglycerol (help info ) or triacylglyceride
..... Click the link for more information.

In anatomy, the intestine is the segment of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine.
..... Click the link for more information.

liver is an organ present in vertebrates and some other animals. It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification.
..... Click the link for more information.

adipose tissue or fat is loose connective tissue composed of adipocytes. Its main role is to store energy in the form of fat, although it also cushions and insulates the body.
..... Click the link for more information.

Very Low Density Lipoprotein (VLDL) is a lipoprotein subclass. 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.
..... Click the link for more information.

Triglyceride (help info ) (more properly known as triacylglycerol (help info ) or triacylglyceride
..... Click the link for more information.

Intermediate density lipoproteins are a class of lipoproteins formed from the degradation of very low density lipoproteins, constituted essentially of triacylglycerols and cholesterol esters.
..... Click the link for more information.

Low-density lipoprotein (LDL) belongs to the lipoprotein particle family. Its size is approx. 22 nm but since LDL particles contain a changing number of fatty acids they actually have a mass and size distribution.
..... Click the link for more information.

High-density lipoproteins (HDL) form a class of lipoproteins, varying somewhat in their size (8–11 nm in diameter), that carry cholesterol from the body's tissues to the liver. About thirty percent of blood cholesterol is carried by HDL.
..... Click the link for more information.

Serum protein electrophoresis is a laboratory test that examines specific proteins in the blood called globulins. Blood must first be collected, usually into an airtight vial or syringe.
..... Click the link for more information.

This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.

Herod_Archelaus

iPedia Free Information Center