|
7α-Hydroxylase Inhibitors
Cholesterol 7 alpha-hydroxylase also known as cholesterol 7-alpha-monooxygenase or cytochrome P450 7A1 (CYP7A1) is an enzyme that in humans is encoded by the gene which has an important role in cholesterol metabolism. It is a cytochrome P450 enzyme, which belongs to the oxidoreductase class, and converts cholesterol to 7-alpha-hydroxycholesterol, the first and rate limiting step in bile acid synthesis. The inhibition of cholesterol 7-alpha-hydroxylase (CYP7A1) represses bile acid biosynthesis. Evolution Sequence comparisons indicated a huge similarity between cytochromes P450 identified in man and bacteria, and suggested that the superfamily cytochrome P450 first originated from a common ancestral gene some three billion years ago. The superfamily cytochrome P450 was named in 1961, because of the 450-nm spectral peak pigment that cytochrome P450 has when reduced and bound to carbon monoxide. In the early 1960s, P450 was thought to be one enzyme, and by the mid 1960s it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the react ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rate-limiting Enzyme
In chemical kinetics, the overall rate of a reaction is often approximately determined by the slowest step, known as the rate-determining step (RDS or RD-step or r/d step) or rate-limiting step. For a given reaction mechanism, the prediction of the corresponding rate equation (for comparison with the experimental rate law) is often simplified by using this approximation of the rate-determining step. In principle, the time evolution of the reactant and product concentrations can be determined from the set of simultaneous rate equations for the individual steps of the mechanism, one for each step. However, the analytical solution of these differential equations is not always easy, and in some cases numerical integration may even be required. The hypothesis of a single rate-determining step can greatly simplify the mathematics. In the simplest case the initial step is the slowest, and the overall rate is just the rate of the first step. Also, the rate equations for mechanisms with a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigenetic Regulation
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "on top of" or "in addition to" the traditional genetic basis for inheritance. Epigenetics most often involves changes that affect the regulation of gene expression, but the term can also be used to describe any heritable phenotypic change. Such effects on cellular and physiological phenotypic traits may result from external or environmental factors, or be part of normal development. The term also refers to the mechanism of changes: functionally relevant alterations to the genome that do not involve mutation of the nucleotide sequence. Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence. Gene expressi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronary Artery Disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic plaque in the arteries of the heart. It is the most common of the cardiovascular diseases. Types include stable angina, unstable angina, myocardial infarction, and sudden cardiac death. A common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn. Usually symptoms occur with exercise or emotional stress, last less than a few minutes, and improve with rest. Shortness of breath may also occur and sometimes no symptoms are present. In many cases, the first sign is a heart attack. Other complications include heart failure or an abnormal heartbeat. Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood choles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-density Lipoprotein Cholesterol
Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall density naming convention), very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL delivers fat molecules to cells. LDL is involved in atherosclerosis, a process in which it is oxidized within the walls of arteries. Overview Lipoproteins transfer lipids (fats) around the body in the extracellular fluid, making fats available to body cells for receptor-mediated endocytosis. Lipoproteins are complex particles composed of multiple proteins, typically 80–100 proteins per particle (organized by a single apolipoprotein B for LDL and the larger particles). A single LDL particle is about 220–275 angstroms in diameter, typically transporting 3,000 to 6,000 f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FGFR4
Fibroblast growth factor receptor 4 is a protein that in humans is encoded by the ''FGFR4'' gene. FGFR4 has also been designated as CD334 (cluster of differentiation 334). The protein encoded by this gene is a member of the fibroblast growth factor receptor family, where amino acid sequence is highly conserved between members and throughout evolution. FGFR family members differ from one another in their ligand affinities and tissue distribution. A full-length representative protein would consist of an extracellular region, composed of three immunoglobulin-like domains, a single hydrophobic membrane-spanning segment and a cytoplasmic tyrosine kinase domain. The extracellular portion of the protein interacts with fibroblast growth factors, setting in motion a cascade of downstream signals, ultimately influencing mitogenesis and differentiation. The genomic organization of this gene, compared to members 1-3, encompasses 18 exons rather than 19 or 20. Although alternative splicing has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FGF15/19
FGF15/19 refers to two orthologous fibroblast growth factors which share 50% aminoacid identity and have similar functions. FGF15 was described in the mouse; FGF19 was found in humans and other species. They share physiological functions and so are often referred to as FGF15/19 or as FGF15/FGF19. They were first described in developing fetal brain. They are now known to be produced in the ileum, and under certain circumstances in the liver and biliary tree. It is thought their principal function is in response to bile acid absorption occurring after meals. FGF15 and FGF19 have similar roles in regulating bile acid synthesis and also glucose metabolism Carbohydrate metabolism is the whole of the biochemical processes responsible for the metabolic formation, breakdown, and interconversion of carbohydrates in living organisms. Carbohydrates are central to many essential metabolic pathways. P ... in the liver. 19 References {{DEFAULTSORT:FGF15 19 Growth factors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sterol Regulatory Element-binding Protein
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that bind to the sterol regulatory element DNA sequence TCACNCCAC. Mammalian SREBPs are encoded by the genes ''SREBF1'' and '' SREBF2''. SREBPs belong to the basic-helix-loop-helix leucine zipper class of transcription factors. Unactivated SREBPs are attached to the nuclear envelope and endoplasmic reticulum membranes. In cells with low levels of sterols, SREBPs are cleaved to a water-soluble N-terminal domain that is translocated to the nucleus. These activated SREBPs then bind to specific sterol regulatory element DNA sequences, thus upregulating the synthesis of enzymes involved in sterol biosynthesis. Sterols in turn inhibit the cleavage of SREBPs and therefore synthesis of additional sterols is reduced through a negative feed back loop. Isoforms Mammalian genomes have two separate SREBP genes ( and ): * SREBP-1 expression produces two different isoforms, SREBP-1a and -1c. These isoforms differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downregulated
In the biological context of organisms' production of gene products, downregulation is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein, in response to an external stimulus. The complementary process that involves increases of such components is called upregulation. An example of downregulation is the cellular decrease in the expression of a specific receptor in response to its increased activation by a molecule, such as a hormone or neurotransmitter, which reduces the cell's sensitivity to the molecule. This is an example of a locally acting (negative feedback) mechanism. An example of upregulation is the response of liver cells exposed to such xenobiotic molecules as dioxin. In this situation, the cells increase their production of cytochrome P450 enzymes, which in turn increases degradation of these dioxin molecules. Downregulation or upregulation of an RNA or protein may also arise by an epigenetic alteration. Such an epigen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liver X Receptor
The liver X receptor (LXR) is a member of the nuclear receptor family of transcription factors and is closely related to nuclear receptors such as the PPARs, FXR and RXR. Liver X receptors (LXRs) are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXRs were earlier classified as orphan nuclear receptors, however, upon discovery of endogenous oxysterols as ligands they were subsequently deorphanized. Two isoforms of LXR have been identified and are referred to as LXRα and LXRβ. The liver X receptors are classified into subfamily 1 (thyroid hormone receptor-like) of the nuclear receptor superfamily, and are given the nuclear receptor nomenclature symbols NR1H3 (LXRα) and NR1H2 (LXRβ) respectively. LXRα and LXRβ were discovered separately between 1994-1995. LXRα isoform was independently identified by two groups and initially named RLD-1 and LXR, whereas four groups identified the LXRβ isoform and called it UR, NER, OR-1, and RIP-15. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Structure Of Cholesterol 7-alpha-hydroxylase
Atomic may refer to: * Of or relating to the atom, the smallest particle of a chemical element that retains its chemical properties * Atomic physics, the study of the atom * Atomic Age, also known as the "Atomic Era" * Atomic scale, distances comparable to the dimensions of an atom * Atom (order theory), in mathematics * Atomic (cocktail), a champagne cocktail * ''Atomic'' (magazine), an Australian computing and technology magazine * Atomic Skis, an Austrian ski producer Music * Atomic (band), a Norwegian jazz quintet * ''Atomic'' (Lit album), 2001 * ''Atomic'' (Mogwai album), 2016 * ''Atomic'', an album by Rockets, 1982 * ''Atomic'' (EP), by , 2013 * "Atomic" (song), by Blondie, 1979 * "Atomic", a song by Tiger Army from '' Tiger Army III: Ghost Tigers Rise'' See also * * * Atom (other) * Atomicity (database systems) * Nuclear (other) * Atomism, philosophy about the basic building blocks of reality * Atomic City (other) * Atomic formula, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Heterodimer Partner
The small heterodimer partner (SHP) also known as NR0B2 (nuclear receptor subfamily 0, group B, member 2) is a protein that in humans is encoded by the ''NR0B2'' gene. SHP is a member of the nuclear receptor family of intracellular transcription factors. SHP is unusual for a nuclear receptor in that it lacks a DNA binding domain. Therefore, it is technically neither a transcription factor nor nuclear receptor but nevertheless it is still classified as such due to relatively high sequence homology with other nuclear receptor family members. Function The principal role of SHP appears to be repression of other nuclear receptors through association to produce a non-productive heterodimer. The protein has also been identified as a mediating factor in the metabolic circadian clock Research shows that it interacts with retinoid and thyroid hormone receptors, inhibiting their ligand-dependent transcriptional activation. In addition, interaction with estrogen receptors has been demon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
