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UGT2B11
UDP glucuronosyltransferase 2 family, polypeptide B4, also known as UGT2B4, is an enzyme that in humans is encoded by the ''UGT2B4'' gene. Function UGT2B4 is mainly involved in the glucuronidation of hyodeoxycholic acid, a bile acid, and catechol-estrogens, such as 17-epiestriol and 4-hydroxy-estrone. The expression of the UGT2B4 enzyme is upregulated by the farnesoid X receptor (FXR), a nuclear receptor In the field of molecular biology, nuclear receptors are a class of proteins responsible for sensing steroids, thyroid hormones, vitamins, and certain other molecules. These receptors work with other proteins to regulate the expression of speci ... which is activated by bile acids. These same bile acids are substrates for the UGT2B4 enzyme. Hence upregulation of UGT2B4 by activated FXR provides a mechanism for the detection, conjugation and subsequent elimination of toxic bile acids. References Further reading * * * * * * * * * * * * * * * * * * * {{gene-4-s ... [...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 reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and 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 noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucuronidation
Glucuronidation is often involved in drug metabolism of substances such as drugs, pollutants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids, and bile acids. These linkages involve glycosidic bonds. Mechanism Glucuronidation consists of transfer of the glucuronic acid component of uridine diphosphate glucuronic acid to a substrate by any of several types of UDP-glucuronosyltransferase. UDP-glucuronic acid (glucuronic acid linked via a glycosidic bond to uridine diphosphate) is an intermediate in the process and is formed in the liver. One example is the N-glucuronidation of an aromatic amine, 4-aminobiphenyl, by UGT1A4 or UGT1A9 from human, rat, or mouse liver. : The substances resulting from glucuronidation are known as glucuronides (or glucuronosides) and are typically much more water-soluble than the non-glucuronic acid-containing substances from which they were originally synthesised. The human body uses glucuronidat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyodeoxycholic Acid
Hyodeoxycholic acid, also known as 3α,6α-Dihydroxy-5β-cholan-24-oic acid or HDCA, is a secondary bile acid, one of the metabolic byproducts of intestinal bacteria. It differs from deoxycholic acid in that the 6α-hydroxyl is in the 12 position in the former. The 6α-hydroxyl group makes HDCA a hydrophilic acid, a property it shares with hyocholic acid. HDCA is present in mammalian species in different proportions. It is the main acid constituent of hog bile, and for this reason it was used industrially as precursor for steroid synthesis before total synthesis became practical. Metabolism In rat intestinal microflora hyodeoxycholic acid is produced by a Gram-positive rod—termed HDCA-1—from several isomers of hyocholic acid and muricholic acid. In pigs with a normal gastrointestinal flora the majority of hyodeoxycholic acid found in bile is of secondary nature, but a small amount was also found in germ free pigs, which supports the hypothesis that HDCA may be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bile Acid
Bile acids are steroid acids found predominantly in the bile of mammals and other vertebrates. Diverse bile acids are synthesized in the liver. Bile acids are conjugated with taurine or glycine residues to give anions called bile salts. Primary bile acids are those synthesized by the liver. Secondary bile acids result from bacterial actions in the colon (anatomy), colon. In humans, taurocholic acid and glycocholic acid (derivatives of cholic acid) and taurochenodeoxycholic acid and glycochenodeoxycholic acid (derivatives of chenodeoxycholic acid) are the major bile salts. They are roughly equal in concentration. The salts of their 7-alpha-dehydroxylated derivatives, deoxycholic acid and lithocholic acid, are also found, with derivatives of cholic, chenodeoxycholic and deoxycholic acids accounting for over 90% of human biliary bile acids. Bile acids comprise about 80% of the organic compounds in bile (others are phospholipids and cholesterol). An increased secretion of bile acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catechol
Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is a toxic organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It was first discovered by destructive distillation of the plant extract catechin. About 20,000 tonnes of catechol are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances. Catechol occurs as feathery white crystals that are very rapidly soluble in water. Isolation and synthesis Catechol was first isolated in 1839 by Edgar Hugo Emil Reinsch (1809–1884) by distilling it from the solid tannic preparation catechin, which is the residuum of catechu, the boiled or concentrated juice of ''Mimosa catechu'' (''Acacia catechu''). Upon heating catechin above its decomposition point, a substance that Reinsch first named ''Brenz-Katechusäure'' (burned catechu acid) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy. Estrogens are synthesized in all vertebrates and some insects. Their presence in both vertebrates and insects suggests that estrogenic sex hormones have an ancient evolutionary history. Quantitatively, estrogens circulate at lower levels than androgens in both men and women. While estrogen levels are significantly lower in males than in females, estrogens nevertheless have important physiological roles in males. Like all steroid hormones, estrogens readily diffuse across the cell membrane. Once inside the cell, they bind to and activate estrogen receptors (E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epiestriol
Epiestriol () (brand names Actriol, Arcagynil, Klimadoral), or epioestriol (), also known as 16β-epiestriol or simply 16-epiestriol as well as 16β-hydroxy-17β-estradiol, is a minor and weak endogenous estrogen, and the 16β-epimer of estriol (which is 16α-hydroxy-17β-estradiol). Epiestriol is (or has previously been) used clinically in the treatment of acne. In addition to its estrogenic actions, epiestriol has been found to possess significant anti-inflammatory properties without glycogenic activity or immunosuppressive effects, an interesting finding that is in contrast to conventional anti-inflammatory steroids like hydrocortisone (a glucocorticoid). See also * 17α-Epiestriol * 16β,17α-Epiestriol * Epimestrol * Mytatrienediol Mytatrienediol (developmental code name SC-6924; former tentative brand names Manvene, Anvene), also known as 16α-methyl-16β-epiestriol 3-methyl ether or 16β-hydroxy-16α-methylestradiol 3-methyl ether, is a synthetic steroidal estr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrone
Estrone (E1), also spelled oestrone, is a steroid, a weak estrogen, and a minor female sex hormone. It is one of three major endogenous estrogens, the others being estradiol and estriol. Estrone, as well as the other estrogens, are synthesized from cholesterol and secreted mainly from the gonads, though they can also be formed from adrenal androgens in adipose tissue. Relative to estradiol, both estrone and estriol have far weaker activity as estrogens. Estrone can be converted into estradiol, and serves mainly as a precursor or metabolic intermediate of estradiol. It is both a precursor and metabolite of estradiol. In addition to its role as a natural hormone, estrone has been used as a medication, for instance in menopausal hormone therapy; for information on estrone as a medication, see the estrone (medication) article. Biological activity Estrone is an estrogen, specifically an agonist of the estrogen receptors ERα and ERβ. It is a far less potent estrogen than is estrad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Farnesoid X Receptor
The bile acid receptor (BAR), also known as farnesoid X receptor (FXR) or NR1H4 (nuclear receptor subfamily 1, group H, member 4), is a nuclear receptor that is encoded by the ''NR1H4'' gene in humans. Function FXR is expressed at high levels in the liver and intestine. Chenodeoxycholic acid and other bile acids are natural ligands for FXR. Similar to other nuclear receptors, when activated, FXR translocates to the cell nucleus, forms a dimer (in this case a heterodimer with RXR) and binds to hormone response elements on DNA, which up- or down-regulates the expression of certain genes. One of the primary functions of FXR activation is the suppression of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis from cholesterol. FXR does not directly bind to the CYP7A1 promoter. Rather, FXR induces expression of small heterodimer partner (SHP), which then functions to inhibit transcription of the CYP7A1 gene. In this way, a negative feedback ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
