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20S-Hydroxycholesterol
20S-Hydroxycholesterol is a steroid of the oxysterol class. It is a human metabolite of cholesterol. 20S-Hydroxycholesterol has been the subject of research into its role in human health. For example, 20S-hydroxycholesterol has been found to be an allosteric activator of the Hedgehog signaling pathway, which has implications in cancer research. More recently, 20S-hydroxycholesterol was identified as an endogenous ligand In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a m ... for the sigma-2 receptor, which had previously been considered an orphan receptor since its discovery in 1990. References {{DEFAULTSORT:Hydroxycholesterol, 20S- Sterols ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma-2 Receptor
The sigma-2 receptor (σ2R) is a sigma receptor subtype that has attracted attention due to its involvement in diseases such as cancer and neurological diseases. It is currently under investigation for its potential diagnostic and therapeutic uses. Although the sigma-2 receptor was identified as a separate pharmacological entity from the sigma-1 receptor in 1990, the gene that codes for the receptor was identified as TMEM97 only in 2017. TMEM97 was shown to regulate the cholesterol transporter NPC1 and to be involved in cholesterol homeostasis. The sigma-2 receptor is a four-pass transmembrane protein located in the endoplasmic reticulum. It has been found to play a role in both hormone signaling and calcium signaling, in neuronal signaling, in cell proliferation and death, and in binding of antipsychotics. Classification The sigma-2 receptor is located in the lipid raft. The sigma-2 receptor is found in several areas of the brain, including high densities in the cerebellum, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and as signaling molecules. Hundreds of steroids are found in plants, animals and fungi. All steroids are manufactured in cells from the sterols lanosterol (opisthokonts) or cycloartenol (plants). Lanosterol and cycloartenol are derived from the cyclization of the triterpene squalene. The steroid core structure is typically composed of seventeen carbon atoms, bonded in four " fused" rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Steroids vary by the functional groups attached to this four-ring core and by the oxidation state of the rings. Sterols are forms of steroids with a hydroxy group at position three and a skeleton derived from cholestane. ''A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxysterol
An oxysterol is a derivative of cholesterol obtained by oxidation involving enzymes and / or pro-oxidants. Such compounds play important roles in various biological processes such as cholesterol homeostasis, lipid metabolism (sphingolipids, fatty acids), apoptosis, autophagy, and prenylation of proteins; the mode of action of oxysterols in these effects is still poorly understood. Several oxysterols are associated with age-related diseases such as cardiovascular disease, eye disease (cataract, age-related macular degeneration), certain neurodegenerative diseases and cancers. The activities of oxysterols in these diseases could be due to their pro-oxidative and pro-inflammatory activities and their ability to act on cellular organelles (mitochondria, peroxisome, lysosome) that can contribute to activate apoptosis and autophagy. There are arguments supporting that oxysterols have important roles in atherosclerosis progression which is involved in several cardiovascular diseases. Ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metabolite
In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, catalytic activity of their own (usually as a cofactor to an enzyme), defense, and interactions with other organisms (e.g. pigments, odorants, and pheromones). A primary metabolite is directly involved in normal "growth", development, and reproduction. Ethylene exemplifies a primary metabolite produced large-scale by industrial microbiology. A secondary metabolite is not directly involved in those processes, but usually has an important ecological function. Examples include antibiotics and pigments such as resins and terpenes etc. Some antibiotics use primary metabolites as precursors, such as actinomycin, which is created from the primary metabolite tryptophan. Some sugars are metabolites, such as fructose or glucose, which are both p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membranes. When chemically isolated, it is a yellowish crystalline solid. Cholesterol also serves as a precursor for the biosynthesis of steroid hormones, bile acid and vitamin D. Cholesterol is the principal sterol synthesized by all animals. In vertebrates, hepatic cells typically produce the greatest amounts. It is absent among prokaryotes (bacteria and archaea), although there are some exceptions, such as '' Mycoplasma'', which require cholesterol for growth. François Poulletier de la Salle first identified cholesterol in solid form in gallstones in 1769. However, it was not until 1815 that chemist Michel Eugène Chevreul named the compound "cholesterine". Etymology The word "cholesterol" comes from the Ancient Greek ''chole-'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allosteric
In biochemistry, allosteric regulation (or allosteric control) is the regulation of an enzyme by binding an effector molecule at a site other than the enzyme's active site. The site to which the effector binds is termed the ''allosteric site'' or ''regulatory site''. Allosteric sites allow effectors to bind to the protein, often resulting in a conformational change and/or a change in protein dynamics. Effectors that enhance the protein's activity are referred to as ''allosteric activators'', whereas those that decrease the protein's activity are called ''allosteric inhibitors''. Allosteric regulations are a natural example of control loops, such as feedback from downstream products or feedforward from upstream substrates. Long-range allostery is especially important in cell signaling. Allosteric regulation is also particularly important in the cell's ability to adjust enzyme activity. The term ''allostery'' comes from the Ancient Greek ''allos'' (), "other", and ''stereos' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hedgehog Signaling Pathway
The Hedgehog signaling pathway is a signaling pathway that transmits information to embryonic cells required for proper cell differentiation. Different parts of the embryo have different concentrations of hedgehog signaling proteins. The pathway also has roles in the adult. Diseases associated with the malfunction of this pathway include cancer. The Hedgehog signaling pathway is one of the key regulators of animal development and is present in all bilaterians. The pathway takes its name from its polypeptide ligand, an intracellular signaling molecule called Hedgehog (''Hh'') found in fruit flies of the genus ''Drosophila''; fruit fly larva lacking the ''Hh'' gene are said to resemble hedgehogs. ''Hh'' is one of Drosophila's segment polarity gene products, involved in establishing the basis of the fly body plan. Larvae without ''Hh'' are short and spiny, resembling the hedgehog animal. The molecule remains important during later stages of embryogenesis and metamorphosis. Mamma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endogenous Ligand
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein. The binding typically results in a change of conformational isomerism (conformation) of the target protein. In DNA-ligand binding studies, the ligand can be a small molecule, ion, or protein which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces. The association or docking is actually reversible through dissociation. Measurably irreversible covalent bonding between a ligand and target molecule is atypical in biological systems. In contrast to the definition of li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orphan Receptor
In biochemistry, an orphan receptor is a protein that has a similar structure to other identified receptors but whose endogenous ligand has not yet been identified. If a ligand for an orphan receptor is later discovered, the receptor is referred to as an "adopted orphan". Conversely, the term orphan ligand refers to a biological ligand whose cognate receptor has not yet been identified. Examples Examples of orphan receptors are found in the G protein-coupled receptor (GPCR) and nuclear receptor families. If an endogenous ligand is found, the orphan receptor is "adopted" or "de-orphanized". An example is the nuclear receptor Farnesoid X receptor (FXR) and the GPCR TGR5/GPCR19/G protein-coupled bile acid receptor, both of which are activated by bile acids. Adopted orphan receptors in the nuclear receptor group include FXR, liver X receptor (LXR), and peroxisome proliferator-activated receptor (PPAR). Another example of an orphan receptor site is the PCP binding site in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Derek Lowe (chemist)
Derek Lowe is a medicinal chemist working on preclinical drug discovery in the pharmaceutical industry. Lowe has published a blog about this field, "In the Pipeline", since 2002 and is a columnist for the Royal Society of Chemistry's '' Chemistry World''. Biography Lowe (born in Harrisburg, Arkansas) got his BA from Hendrix College and his PhD in organic chemistry from Duke University on synthesis of natural products, before spending time in Germany on a Humboldt Fellowship. Lowe was the one of the first people to blog from inside the pharmaceutical industry, with the approval of his supervisor and the company legal department, and one of the first science bloggers. By 2006, his blog had between 3,000 and 4,000 visitors per day during the workweek; he covered business matters, trends and issues in medicinal chemistry, and legal matters like patent law and regulation. At that time he was working at a pharmaceutical company doing hit to lead medical chemistry work. his blog re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature (journal), Nature'' c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
