Centrifugation, Isopycnic
A technique used to separate particles according to their densities in a continuous density gradient. The sample is usually mixed with a solution of known gradient materials and subjected to centrifugation. Each particle sediments to the position at which the gradient density is equal to its own. The range of the density gradient is usually greater than that of the sample particles. It is used in purifying biological materials such as proteins, nucleic acids, organelles, and cell types.
Lipoproteins, HDL
A class of lipoproteins of small size (4-13 nm) and dense (greater than 1.063 g/ml) particles. HDL lipoproteins, synthesized in the liver without a lipid core, accumulate cholesterol esters from peripheral tissues and transport them to the liver for re-utilization or elimination from the body (the reverse cholesterol transport). Their major protein component is APOLIPOPROTEIN A-I. HDL also shuttle APOLIPOPROTEINS C and APOLIPOPROTEINS E to and from triglyceride-rich lipoproteins during their catabolism. HDL plasma level has been inversely correlated with the risk of cardiovascular diseases.
Lipoproteins
Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.
Lipoproteins, LDL
A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues.
Lipoproteins, VLDL
A class of lipoproteins of very light (0.93-1.006 g/ml) large size (30-80 nm) particles with a core composed mainly of TRIGLYCERIDES and a surface monolayer of PHOSPHOLIPIDS and CHOLESTEROL into which are imbedded the apolipoproteins B, E, and C. VLDL facilitates the transport of endogenously made triglycerides to extrahepatic tissues. As triglycerides and Apo C are removed, VLDL is converted to INTERMEDIATE-DENSITY LIPOPROTEINS, then to LOW-DENSITY LIPOPROTEINS from which cholesterol is delivered to the extrahepatic tissues.
Lipoprotein Lipase
An enzyme of the hydrolase class that catalyzes the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. The enzyme hydrolyzes triacylglycerols in chylomicrons, very-low-density lipoproteins, low-density lipoproteins, and diacylglycerols. It occurs on capillary endothelial surfaces, especially in mammary, muscle, and adipose tissue. Genetic deficiency of the enzyme causes familial hyperlipoproteinemia Type I. (Dorland, 27th ed) EC 3.1.1.34.
Lipoprotein(a)
A lipoprotein that resembles the LOW-DENSITY LIPOPROTEINS but with an extra protein moiety, APOPROTEIN (A) also known as APOLIPOPROTEIN (A), linked to APOLIPOPROTEIN B-100 on the LDL by one or two disulfide bonds. High plasma level of lipoprotein (a) is associated with increased risk of atherosclerotic cardiovascular disease.
Cholesterol, HDL
Cholesterol which is contained in or bound to high-density lipoproteins (HDL), including CHOLESTEROL ESTERS and free cholesterol.
Lipoproteins, HDL2
Low-density subclass of the high-density lipoproteins, with particle sizes between 8 to 13 nm.
Cholesterol
Receptors, Lipoprotein
Cell surface proteins that bind lipoproteins with high affinity. Lipoprotein receptors in the liver and peripheral tissues mediate the regulation of plasma and cellular cholesterol metabolism and concentration. The receptors generally recognize the apolipoproteins of the lipoprotein complex, and binding is often a trigger for endocytosis.
Apolipoproteins
Protein components on the surface of LIPOPROTEINS. They form a layer surrounding the hydrophobic lipid core. There are several classes of apolipoproteins with each playing a different role in lipid transport and LIPID METABOLISM. These proteins are synthesized mainly in the LIVER and the INTESTINES.
Triglycerides
Apolipoproteins B
Major structural proteins of triacylglycerol-rich LIPOPROTEINS. There are two forms, apolipoprotein B-100 and apolipoprotein B-48, both derived from a single gene. ApoB-100 expressed in the liver is found in low-density lipoproteins (LIPOPROTEINS, LDL; LIPOPROTEINS, VLDL). ApoB-48 expressed in the intestine is found in CHYLOMICRONS. They are important in the biosynthesis, transport, and metabolism of triacylglycerol-rich lipoproteins. Plasma Apo-B levels are high in atherosclerotic patients but non-detectable in ABETALIPOPROTEINEMIA.
Lipoproteins, HDL3
Intermediate-density subclass of the high-density lipoproteins, with particle sizes between 7 to 8 nm. As the larger lighter HDL2 lipoprotein, HDL3 lipoprotein is lipid-rich.
Receptors, LDL
Receptors on the plasma membrane of nonhepatic cells that specifically bind LDL. The receptors are localized in specialized regions called coated pits. Hypercholesteremia is caused by an allelic genetic defect of three types: 1, receptors do not bind to LDL; 2, there is reduced binding of LDL; and 3, there is normal binding but no internalization of LDL. In consequence, entry of cholesterol esters into the cell is impaired and the intracellular feedback by cholesterol on 3-hydroxy-3-methylglutaryl CoA reductase is lacking.
Lipoproteins, IDL
A mixture of very-low-density lipoproteins (VLDL), particularly the triglyceride-poor VLDL, with slow diffuse electrophoretic mobilities in the beta and alpha2 regions which are similar to that of beta-lipoproteins (LDL) or alpha-lipoproteins (HDL). They can be intermediate (remnant) lipoproteins in the de-lipidation process, or remnants of mutant CHYLOMICRONS and VERY-LOW-DENSITY LIPOPROTEINS which cannot be metabolized completely as seen in FAMILIAL DYSBETALIPOPROTEINEMIA.
Cholesterol, LDL
Cholesterol which is contained in or bound to low density lipoproteins (LDL), including CHOLESTEROL ESTERS and free cholesterol.
Cholesterol Esters
Fatty acid esters of cholesterol which constitute about two-thirds of the cholesterol in the plasma. The accumulation of cholesterol esters in the arterial intima is a characteristic feature of atherosclerosis.
Lipids
A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)
Apolipoproteins A
Structural proteins of the alpha-lipoproteins (HIGH DENSITY LIPOPROTEINS), including APOLIPOPROTEIN A-I and APOLIPOPROTEIN A-II. They can modulate the activity of LECITHIN CHOLESTEROL ACYLTRANSFERASE. These apolipoproteins are low in atherosclerotic patients. They are either absent or present in extremely low plasma concentration in TANGIER DISEASE.
Apolipoproteins E
A class of protein components which can be found in several lipoproteins including HIGH-DENSITY LIPOPROTEINS; VERY-LOW-DENSITY LIPOPROTEINS; and CHYLOMICRONS. Synthesized in most organs, Apo E is important in the global transport of lipids and cholesterol throughout the body. Apo E is also a ligand for LDL receptors (RECEPTORS, LDL) that mediates the binding, internalization, and catabolism of lipoprotein particles in cells. There are several allelic isoforms (such as E2, E3, and E4). Deficiency or defects in Apo E are causes of HYPERLIPOPROTEINEMIA TYPE III.
Apolipoprotein A-II
The second most abundant protein component of HIGH DENSITY LIPOPROTEINS or HDL. It has a high lipid affinity and is known to displace APOLIPOPROTEIN A-I from HDL particles and generates a stable HDL complex. ApoA-II can modulate the activation of LECITHIN CHOLESTEROL ACYLTRANSFERASE in the presence of APOLIPOPROTEIN A-I, thus affecting HDL metabolism.
Chylomicrons
A class of lipoproteins that carry dietary CHOLESTEROL and TRIGLYCERIDES from the SMALL INTESTINE to the tissues. Their density (0.93-1.006 g/ml) is the same as that of VERY-LOW-DENSITY LIPOPROTEINS.
Hyperlipidemias
Conditions with excess LIPIDS in the blood.
Low Density Lipoprotein Receptor-Related Protein-1
Lipase
An enzyme of the hydrolase class that catalyzes the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. It is produced by glands on the tongue and by the pancreas and initiates the digestion of dietary fats. (From Dorland, 27th ed) EC 3.1.1.3.
Apolipoprotein B-100
A 513-kDa protein synthesized in the LIVER. It serves as the major structural protein of low-density lipoproteins (LIPOPROTEINS, LDL; LIPOPROTEINS, VLDL). It is the ligand for the LDL receptor (RECEPTORS, LDL) that promotes cellular binding and internalization of LDL particles.
Cholesterol, VLDL
Cholesterol which is contained in or bound to very low density lipoproteins (VLDL). High circulating levels of VLDL cholesterol are found in HYPERLIPOPROTEINEMIA TYPE IIB. The cholesterol on the VLDL is eventually delivered by LOW-DENSITY LIPOPROTEINS to the tissues after the catabolism of VLDL to INTERMEDIATE-DENSITY LIPOPROTEINS, then to LDL.
Ultracentrifugation
Cholesterol Ester Transfer Proteins
Proteins that bind to and transfer CHOLESTEROL ESTERS between LIPOPROTEINS such as LOW-DENSITY LIPOPROTEINS and HIGH-DENSITY LIPOPROTEINS.
Phosphatidylcholine-Sterol O-Acyltransferase
An enzyme secreted from the liver into the plasma of many mammalian species. It catalyzes the esterification of the hydroxyl group of lipoprotein cholesterol by the transfer of a fatty acid from the C-2 position of lecithin. In familial lecithin:cholesterol acyltransferase deficiency disease, the absence of the enzyme results in an excess of unesterified cholesterol in plasma. EC 2.3.1.43.
Arteriosclerosis
Thickening and loss of elasticity of the walls of ARTERIES of all sizes. There are many forms classified by the types of lesions and arteries involved, such as ATHEROSCLEROSIS with fatty lesions in the ARTERIAL INTIMA of medium and large muscular arteries.
Liver
Apolipoprotein A-I
The most abundant protein component of HIGH DENSITY LIPOPROTEINS or HDL. This protein serves as an acceptor for CHOLESTEROL released from cells thus promoting efflux of cholesterol to HDL then to the LIVER for excretion from the body (reverse cholesterol transport). It also acts as a cofactor for LECITHIN CHOLESTEROL ACYLTRANSFERASE that forms CHOLESTEROL ESTERS on the HDL particles. Mutations of this gene APOA1 cause HDL deficiency, such as in FAMILIAL ALPHA LIPOPROTEIN DEFICIENCY DISEASE and in some patients with TANGIER DISEASE.
Scavenger Receptors, Class B
A family of scavenger receptors that are predominately localized to CAVEOLAE of the PLASMA MEMBRANE and bind HIGH DENSITY LIPOPROTEINS.
Hypertriglyceridemia
A condition of elevated levels of TRIGLYCERIDES in the blood.
Apolipoproteins C
A group of apolipoproteins that can readily exchange among the various classes of lipoproteins (HDL; VLDL; CHYLOMICRONS). After lipolysis of TRIGLYCERIDES on VLDL and chylomicrons, Apo-C proteins are normally transferred to HDL. The subtypes can modulate remnant binding to receptors, LECITHIN CHOLESTEROL ACYLTRANSFERASE, or LIPOPROTEIN LIPASE.
Lipid Metabolism
Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.
Hyperlipoproteinemias
Conditions with abnormally elevated levels of LIPOPROTEINS in the blood. They may be inherited, acquired, primary, or secondary. Hyperlipoproteinemias are classified according to the pattern of lipoproteins on electrophoresis or ultracentrifugation.
Hypercholesterolemia
A condition with abnormally high levels of CHOLESTEROL in the blood. It is defined as a cholesterol value exceeding the 95th percentile for the population.
Receptors, Scavenger
A large group of structurally diverse cell surface receptors that mediate endocytic uptake of modified LIPOPROTEINS. Scavenger receptors are expressed by MYELOID CELLS and some ENDOTHELIAL CELLS, and were originally characterized based on their ability to bind acetylated LOW-DENSITY LIPOPROTEINS. They can also bind a variety of other polyanionic ligand. Certain scavenger receptors can internalize micro-organisms as well as apoptotic cells.
Phospholipids
Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.
Apolipoprotein C-III
A 9-kDa protein component of VERY-LOW-DENSITY LIPOPROTEINS and CHYLOMICRON REMNANTS. Apo C-III, synthesized in the liver, is an inhibitor of LIPOPROTEIN LIPASE. Apo C-III modulates the binding of chylomicron remnants and VLDL to receptors (RECEPTORS, LDL) thus decreases the uptake of triglyceride-rich particles by the liver cells and subsequent degradation. The normal Apo C-III is glycosylated. There are several polymorphic forms with varying amounts of SIALIC ACID (Apo C-III-0, Apo C-III-1, and Apo C-III-2).
High-Density Lipoproteins, Pre-beta
A highly dense subclass of the high-density lipoproteins, with particle sizes below 7 nm. They are also known as nascent HDL, composed of a few APOLIPOPROTEIN A-I molecules which are complexed with PHOSPHOLIPIDS. The lipid-poor pre-beta-HDL particles serve as progenitors of HDL3 and then HDL2 after absorption of free cholesterol from cell membranes, cholesterol esterification, and acquisition of apolipoproteins A-II, Cs, and E. Pre-beta-HDL initiate the reverse cholesterol transport process from cells to liver.
Apolipoprotein B-48
A 241-kDa protein synthesized only in the INTESTINES. It serves as a structural protein of CHYLOMICRONS. Its exclusive association with chylomicron particles provides an indicator of intestinally derived lipoproteins in circulation. Apo B-48 is a shortened form of apo B-100 and lacks the LDL-receptor region.
Atherosclerosis
Hyperlipoproteinemia Type II
A group of familial disorders characterized by elevated circulating cholesterol contained in either LOW-DENSITY LIPOPROTEINS alone or also in VERY-LOW-DENSITY LIPOPROTEINS (pre-beta lipoproteins).
Apolipoprotein C-II
A 9-kDa protein component of VERY-LOW-DENSITY LIPOPROTEINS. It contains a cofactor for LIPOPROTEIN LIPASE and activates several triacylglycerol lipases. The association of Apo C-II with plasma CHYLOMICRONS; VLDL, and HIGH-DENSITY LIPOPROTEINS is reversible and changes rapidly as a function of triglyceride metabolism. Clinically, Apo C-II deficiency is similar to lipoprotein lipase deficiency (HYPERLIPOPROTEINEMIA TYPE I) and is therefore called hyperlipoproteinemia type IB.
Dietary Fats
Antigens, CD36
Leukocyte differentiation antigens and major platelet membrane glycoproteins present on MONOCYTES; ENDOTHELIAL CELLS; PLATELETS; and mammary EPITHELIAL CELLS. They play major roles in CELL ADHESION; SIGNAL TRANSDUCTION; and regulation of angiogenesis. CD36 is a receptor for THROMBOSPONDINS and can act as a scavenger receptor that recognizes and transports oxidized LIPOPROTEINS and FATTY ACIDS.
ATP Binding Cassette Transporter 1
A superfamily of large integral ATP-binding cassette membrane proteins whose expression pattern is consistent with a role in lipid (cholesterol) efflux. It is implicated in TANGIER DISEASE characterized by accumulation of cholesteryl ester in various tissues.
Aryldialkylphosphatase
An enzyme which catalyzes the hydrolysis of an aryl-dialkyl phosphate to form dialkyl phosphate and an aryl alcohol. It can hydrolyze a broad spectrum of organophosphate substrates and a number of aromatic carboxylic acid esters. It may also mediate an enzymatic protection of LOW DENSITY LIPOPROTEINS against oxidative modification and the consequent series of events leading to ATHEROMA formation. The enzyme was previously regarded to be identical with Arylesterase (EC 3.1.1.2).
Carrier Proteins
Hypolipidemic Agents
Substances that lower the levels of certain LIPIDS in the BLOOD. They are used to treat HYPERLIPIDEMIAS.
Hypolipoproteinemias
Conditions with abnormally low levels of LIPOPROTEINS in the blood. This may involve any of the lipoprotein subclasses, including ALPHA-LIPOPROTEINS (high-density lipoproteins); BETA-LIPOPROTEINS (low-density lipoproteins); and PREBETA-LIPOPROTEINS (very-low-density lipoproteins).
Cells, Cultured
Anticholesteremic Agents
Substances used to lower plasma CHOLESTEROL levels.
Oxidation-Reduction
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
Apoprotein(a)
A large and highly glycosylated protein constituent of LIPOPROTEIN (A). It has very little affinity for lipids but forms disulfide-linkage to APOLIPOPROTEIN B-100. Apoprotein(a) has SERINE PROTEINASE activity and can be of varying sizes from 400- to 800-kDa. It is homologous to PLASMINOGEN and is known to modulate THROMBOSIS and FIBRINOLYSIS.
Hyperlipoproteinemia Type IV
A hypertriglyceridemia disorder, often with autosomal dominant inheritance. It is characterized by the persistent elevations of plasma TRIGLYCERIDES, endogenously synthesized and contained predominantly in VERY-LOW-DENSITY LIPOPROTEINS (pre-beta lipoproteins). In contrast, the plasma CHOLESTEROL and PHOSPHOLIPIDS usually remain within normal limits.
Phospholipid Transfer Proteins
A ubiquitous family of proteins that transport PHOSPHOLIPIDS such as PHOSPHATIDYLINOSITOL and PHOSPHATIDYLCHOLINE between membranes. They play an important role in phospholipid metabolism during vesicular transport and SIGNAL TRANSDUCTION.
Dyslipidemias
Abnormalities in the serum levels of LIPIDS, including overproduction or deficiency. Abnormal serum lipid profiles may include high total CHOLESTEROL, high TRIGLYCERIDES, low HIGH DENSITY LIPOPROTEIN CHOLESTEROL, and elevated LOW DENSITY LIPOPROTEIN CHOLESTEROL.
Macrophages
The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)
Tangier Disease
An autosomal recessively inherited disorder caused by mutation of ATP-BINDING CASSETTE TRANSPORTERS involved in cellular cholesterol removal (reverse-cholesterol transport). It is characterized by near absence of ALPHA-LIPOPROTEINS (high-density lipoproteins) in blood. The massive tissue deposition of cholesterol esters results in HEPATOMEGALY; SPLENOMEGALY; RETINITIS PIGMENTOSA; large orange tonsils; and often sensory POLYNEUROPATHY. The disorder was first found among inhabitants of Tangier Island in the Chesapeake Bay, MD.
Lipolysis
The metabolic process of breaking down LIPIDS to release FREE FATTY ACIDS, the major oxidative fuel for the body. Lipolysis may involve dietary lipids in the DIGESTIVE TRACT, circulating lipids in the BLOOD, and stored lipids in the ADIPOSE TISSUE or the LIVER. A number of enzymes are involved in such lipid hydrolysis, such as LIPASE and LIPOPROTEIN LIPASE from various tissues.
Hyperlipoproteinemia Type I
An inherited condition due to a deficiency of either LIPOPROTEIN LIPASE or APOLIPOPROTEIN C-II (a lipase-activating protein). The lack of lipase activities results in inability to remove CHYLOMICRONS and TRIGLYCERIDES from the blood which has a creamy top layer after standing.
Esterification
The process of converting an acid into an alkyl or aryl derivative. Most frequently the process consists of the reaction of an acid with an alcohol in the presence of a trace of mineral acid as catalyst or the reaction of an acyl chloride with an alcohol. Esterification can also be accomplished by enzymatic processes.
Foam Cells
Lipid-laden macrophages originating from monocytes or from smooth muscle cells.
Heparin
A highly acidic mucopolysaccharide formed of equal parts of sulfated D-glucosamine and D-glucuronic acid with sulfaminic bridges. The molecular weight ranges from six to twenty thousand. Heparin occurs in and is obtained from liver, lung, mast cells, etc., of vertebrates. Its function is unknown, but it is used to prevent blood clotting in vivo and vitro, in the form of many different salts.
Biological Transport
Risk Factors
Electrophoresis, Polyacrylamide Gel
Abetalipoproteinemia
An autosomal recessive disorder of lipid metabolism. It is caused by mutation of the microsomal triglyceride transfer protein that catalyzes the transport of lipids (TRIGLYCERIDES; CHOLESTEROL ESTERS; PHOSPHOLIPIDS) and is required in the secretion of BETA-LIPOPROTEINS (low density lipoproteins or LDL). Features include defective intestinal lipid absorption, very low serum cholesterol level, and near absent LDL.
Fatty Acids
Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)
Coronary Disease
ATP-Binding Cassette Transporters
Lecithin Acyltransferase Deficiency
An autosomal recessively inherited disorder caused by mutation of LECITHIN CHOLESTEROL ACYLTRANSFERASE that facilitates the esterification of lipoprotein cholesterol and subsequent removal from peripheral tissues to the liver. This defect results in low HDL-cholesterol level in blood and accumulation of free cholesterol in tissue leading to a triad of CORNEAL OPACITY, hemolytic anemia (ANEMIA, HEMOLYTIC), and PROTEINURIA.
Apoproteins
The protein components of a number of complexes, such as enzymes (APOENZYMES), ferritin (APOFERRITINS), or lipoproteins (APOLIPOPROTEINS).
Rabbits
Scavenger Receptors, Class E
Hydroxymethylglutaryl-CoA Reductase Inhibitors
Compounds that inhibit HMG-CoA reductases. They have been shown to directly lower cholesterol synthesis.
Receptors, Immunologic
Hyperlipoproteinemia Type III
An autosomal recessively inherited disorder characterized by the accumulation of intermediate-density lipoprotein (IDL or broad-beta-lipoprotein). IDL has a CHOLESTEROL to TRIGLYCERIDES ratio greater than that of VERY-LOW-DENSITY LIPOPROTEINS. This disorder is due to mutation of APOLIPOPROTEINS E, a receptor-binding component of VLDL and CHYLOMICRONS, resulting in their reduced clearance and high plasma levels of both cholesterol and triglycerides.
Sterol O-Acyltransferase
An enzyme that catalyzes the formation of cholesterol esters by the direct transfer of the fatty acid group from a fatty acyl CoA derivative. This enzyme has been found in the adrenal gland, gonads, liver, intestinal mucosa, and aorta of many mammalian species. EC 2.3.1.26.
Glycoproteins
Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.
Phosphatidylcholines
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.
Apolipoprotein E3
A 34-kDa glycosylated protein. A major and most common isoform of apolipoprotein E. Therefore, it is also known as apolipoprotein E (ApoE). In human, Apo E3 is a 299-amino acid protein with a cysteine at the 112 and an arginine at the 158 position. It is involved with the transport of TRIGLYCERIDES; PHOSPHOLIPIDS; CHOLESTEROL; and CHOLESTERYL ESTERS in and out of the cells.
Cardiovascular Diseases
Probucol
A drug used to lower LDL and HDL cholesterol yet has little effect on serum-triglyceride or VLDL cholesterol. (From Martindale, The Extra Pharmacopoeia, 30th ed, p993).
Hyperlipidemia, Familial Combined
A type of familial lipid metabolism disorder characterized by a variable pattern of elevated plasma CHOLESTEROL and/or TRIGLYCERIDES. Multiple genes on different chromosomes may be involved, such as the major late transcription factor (UPSTREAM STIMULATORY FACTORS) on CHROMOSOME 1.
Niacin
Electrophoresis, Agar Gel
Protein Binding
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Hydroxymethylglutaryl CoA Reductases
Mice, Inbred C57BL
Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.
1-Alkyl-2-acetylglycerophosphocholine Esterase
A lipoprotein-associated PHOSPHOLIPASE A2 which modulates the action of PLATELET ACTIVATING FACTOR by hydrolyzing the SN-2 ester bond to yield the biologically inactive lyso-platelet-activating factor. It has specificity for phospholipid substrates with short-chain residues at the SN-2 position, but inactive against long-chain phospholipids. Deficiency in this enzyme is associated with many diseases including ASTHMA, and HYPERCHOLESTEROLEMIA.
Oleic Acid
Mice, Knockout
Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.
Apolipoprotein C-I
A 6.6-kDa protein component of VERY-LOW-DENSITY LIPOPROTEINS; INTERMEDIATE-DENSITY LIPOPROTEINS; and HIGH-DENSITY LIPOPROTEINS. Apo C-I displaces APO E from lipoproteins, modulate their binding to receptors (RECEPTORS, LDL), and thereby decrease their clearance from plasma. Elevated Apo C-I levels are associated with HYPERLIPOPROTEINEMIA and ATHEROSCLEROSIS.
Oleic Acids
A group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 carbon.
Adipose Tissue
Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.
Reference Values
Biological Markers
Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.
LDL-Receptor Related Proteins
A family of proteins that share sequence similarity with the low density lipoprotein receptor (RECEPTORS, LDL).
Lipid Peroxidation
Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.
RNA, Messenger
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
Iodine Radioisotopes
Lovastatin
A fungal metabolite isolated from cultures of Aspergillus terreus. The compound is a potent anticholesteremic agent. It inhibits 3-hydroxy-3-methylglutaryl coenzyme A reductase (HYDROXYMETHYLGLUTARYL COA REDUCTASES), which is the rate-limiting enzyme in cholesterol biosynthesis. It also stimulates the production of low-density lipoprotein receptors in the liver.