ABCG8
ATP-binding cassette sub-family G member 8 is a protein that in humans is encoded by the ''ABCG8'' gene. The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. The protein encoded by this gene functions as a half-transporter to limit intestinal absorption and promote biliary excretion of sterols. It is expressed in a tissue-specific manner in the liver, colon, and intestine. This gene is tandemly arrayed on chromosome 2, in a head-to-head orientation with family member ABCG5. Mutations in this gene may contribute to sterol accumulation and atherosclerosis, and have been observed in patients with sitosterolemia. A loss-of-function mutation in ABCG8 impairs the removal of sterols from cells and, in ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Sitosterolemia
Sitosterolemia, also known as phytosterolemia, is a rare autosomal recessively inherited lipid metabolic disorder. It is characterized by hyperabsorption and decreased biliary excretion of dietary sterols (including the phytosterol beta-sitosterol). Healthy persons absorb only about 5% of dietary plant sterols, but sitosterolemia patients absorb 15% to 60% of ingested sitosterol without excreting much into the bile. It's named after the most abundant phytosterol in the diet, sitosterol, though other phytosterols are also involved. The phytosterol campesterol is more readily absorbed than sitosterol. Sitosterolemia patients develop hypercholesterolemia, tendon and tuberous xanthomas, premature development of atherosclerosis, and abnormal hematologic and liver function test results. Signs and symptoms Sitosterolemia may share several clinical characteristics with the well-characterized familial hypercholesterolemia (FH), such as the development of tendon xanthomas in the first ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of Gene product, RNA or protein from a gene), DNA is first transcription (biology), copied into RNA. RNA can be non-coding RNA, directly functional or be the intermediate protein biosynthesis, template for the synthesis of a protein. The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the gene pool of the population (biology), population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Intra-cellular Membrane
The endomembrane system is composed of the different membranes (endomembranes) that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles. In eukaryotes the organelles of the endomembrane system include: the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, endosomes, and plasma (cell) membrane among others. The system is defined more accurately as the set of membranes that forms a single functional and developmental unit, either being connected directly, or exchanging material through vesicle transport. Importantly, the endomembrane system does not include the membranes of plastids or mitochondria, but might have evolved partially from the actions of the latter (see below). The nuclear membrane contains a lipid bilayer that encompasses the contents of the nucleus. The endoplasmic reticulum (ER) is a synthesis and transport organelle that branches int ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Sterol
A sterol is any organic compound with a Skeletal formula, skeleton closely related to Cholestanol, cholestan-3-ol. The simplest sterol is gonan-3-ol, which has a formula of , and is derived from that of gonane by replacement of a hydrogen atom on C3 position by a hydroxyl group. It is therefore an alcohol (chemistry), alcohol of gonane. More generally, any compounds that contain the gonane structure, additional functional groups, and/or modified ring systems derived from gonane are called steroids. Therefore, sterols are a subgroup of the steroids. They occur naturally in most Eukaryote, eukaryotes, including plants, animals, and fungi, and can also be produced by some bacteria (however likely with different functions). The most familiar type of animal sterol is cholesterol, which is vital to the structure of the cell membrane, and functions as a precursor to fat-soluble vitamins and steroid hormones. While technically alcohols, sterols are classified by biochemists as lipids (f ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Gallbladder Disease
Gallbladder diseases are diseases involving the gallbladder and is closely linked to biliary disease, with the most common cause being gallstones (cholelithiasis). The gallbladder is designed to aid in the digestion of fats by concentrating and storing the bile made in the liver and transferring it through the biliary tract to the digestive system through bile ducts that connect the liver, gallbladder, and the Sphincter of Oddi. The gallbladder is controlled on a neurohormonal basis, with Cholecystokinin (CCK) leading to the contraction and release of bile into the bile ducts. Other hormones allow for the relaxation and further storing of bile. A disruption in the hormones, ducts, or gallbladder can lead to disease. Gallstones are the most common disease and can lead to other diseases, including Cholecystitis, inflammation of the gallbladder, and gallstone pancreatitis when the gallstone blocks the pancreatic duct. Treatment is considered for symptomatic disease and can vary from ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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ATP-binding Cassette Transporter
The ABC transporters, ATP synthase (ATP)-binding cassette transporters are a transport system superfamily that is one of the largest and possibly one of the oldest gene family, gene families. It is represented in all extant taxon, extant Phylum, phyla, from prokaryotes to humans. ABC transporters belong to translocases. ABC transporters often consist of multiple subunits, one or two of which are transmembrane proteins and one or two of which are membrane-associated AAA proteins, AAA ATPases. The ATPase subunits utilize the energy of adenosine triphosphate (ATP) binding and hydrolysis to provide the energy needed for the translocation of substrates across membranes, either for uptake or for export of the substrate. Most of the uptake systems also have an extracytoplasmic receptor, a solute binding protein. Some homologous ATPases function in non-transport-related processes such as RNA translation, translation of RNA and DNA repair. ABC transporters are considered to be an ABC ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |