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Cholecystokinin
Cholecystokinin (CCK or CCK-PZ; from Greek ''chole'', "bile"; ''cysto'', "sac"; ''kinin'', "move"; hence, ''move the bile-sac (gallbladder)'') is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, formerly called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum, the first segment of the small intestine. Its presence causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively, and also acts as a hunger suppressant. History Evidence that the small intestine controls the release of bile was uncovered as early as 1856, when French physiologist Claude Bernard showed that when dilute acetic acid was applied to the orifice of the bile duct, the duct released bile into the duodenum. In 1903 the French physiologist showed that this reflex was not mediated by the nervous system. In 1904 the French physiologist Charles Fleig showed that the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholecystokinin A Receptor
The Cholecystokinin A receptor is a human protein, also known as CCKAR or CCK1, with CCK1 now being the IUPHAR-recommended name. Function This gene encodes a G-protein coupled receptor that binds sulfated members of the cholecystokinin (CCK) family of peptide hormones. This receptor is a major physiologic mediator of pancreatic enzyme secretion and smooth muscle contraction of the gallbladder and stomach. In the central and peripheral nervous system this receptor regulates satiety and the release of beta-endorphin and dopamine. The extracellular, N-terminal, domain of this protein adopts a tertiary structure consisting of a few helical turns and a disulfide-cross linked loop. It is required for interaction of the cholecystokinin A receptor with its corresponding hormonal ligand. Selective Ligands Agonists * Cholecystokinin Cholecystokinin (CCK or CCK-PZ; from Greek ''chole'', "bile"; ''cysto'', "sac"; ''kinin'', "move"; hence, ''move the bile-sac (gallbladder)'') is a pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCK Receptor
Cholecystokinin receptors or CCK receptors are a group of G-protein coupled receptors which bind the peptide hormones cholecystokinin (CCK) and gastrin. There are two different subtypes CCKA and CCKB which are ~50% homologous: Various cholecystokinin antagonists have been developed and are used in research, although the only drug of this class that has been widely marketed to date is the anti-ulcer drug proglumide Proglumide (Milid) is a drug that inhibits gastrointestinal motility and reduces gastric secretions. It acts as a cholecystokinin antagonist, which blocks both the CCKA and CCKB subtypes. It was used mainly in the treatment of stomach ulcers, .... References External links * G protein-coupled receptors {{Cell-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digestive Enzymes
Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption into the cells of the body. Digestive enzymes are found in the digestive tracts of animals (including humans) and in the tracts of carnivorous plants, where they aid in the digestion of food, as well as inside cells, especially in their lysosomes, where they function to maintain cellular survival. Digestive enzymes of diverse specificities are found in the saliva secreted by the salivary glands, in the secretions of cells lining the stomach, in the pancreatic juice secreted by pancreatic exocrine cells, and in the secretions of cells lining the small and large intestines. Digestive enzymes are classified based on their target substrates: * Lipases split fatty acids into fats and oils. *Proteases and peptidases split proteins into small peptides and amino acids. *Amylases split carbohydrates such as starch and sugars in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrin
Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. Gastrin binds to cholecystokinin B receptors to stimulate the release of histamines in enterochromaffin-like cells, and it induces the insertion of K+/H+ ATPase pumps into the apical membrane of parietal cells (which in turn increases H+ release into the stomach cavity). Its release is stimulated by peptides in the Lumen (anatomy), lumen of the stomach. Physiology Genetics In humans, the ''GAS'' gene is located on the long arm of the seventeenth chromosome (17q21). Synthesis Gastrin is a linear peptide hormone produced by G cells of the duodenum and in the pyloric antrum of the stomach. It is secreted into the bloodstream. The encoded polypeptide is preprogastrin, which is cleaved by enzymes in posttranslational modification to produce progastr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrointestinal Hormone
The gastrointestinal hormones (or gut hormones) constitute a group of hormones secreted by enteroendocrine cells in the stomach, pancreas, and small intestine that control various functions of the digestive organs. Later studies showed that most of the gut peptides, such as secretin, cholecystokinin or substance P, were found to play a role of neurotransmitters and neuromodulators in the central and peripheral nervous systems. Enteroendocrine cells do not form glands but are spread throughout the digestive tract. They exert their autocrine and paracrine actions that integrate gastrointestinal function. Types The gastrointestinal hormonesVella A and Drucker DJ (2011)Chapter 39 Gastrointestinal Hormones and Gut Endocrine Tumors, pp 1697-1707. In Williams Textbook of Endocrinology (2011, 12th edition) can be divided into three main groups based upon their chemical structure. * '' Gastrin–cholecystokinin family'': gastrin and cholecystokinin * ''Secretin family'': secretin, glucagon, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pancreas
The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin, and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins, and fats in food entering the duodenum from the stomach. Inflammation of the pancreas is known as pancreatitis, with common causes including chronic alcohol use and gallstones. Becaus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erik Jorpes
Johan Erik Jorpes (born Johansson, 15 July 1894 – 10 July 1973) was a Finnish-born Swedish physician and biochemist. He identified the chemical structure of heparin and developed its clinical applications. Jorpes was the professor of medical chemistry in the Karolinska Institute in Stockholm in 1946–1963. Early life Erik Jorpes was born as Johan Erik Johansson to a poor fisherman's family in the village of Överboda in Kökar in Åland. The family lived in a house called ''Jorpes'', which he later adopted as his last name to replace the patronyme ''Johansson''. After the primary school, his parents send the talented kid to high school in Turku. Other students of the Swedish-language ''Svenska klassiska lyceum'' came mostly from wealthy upper-class families, Jorpes was bullied of his social status and dialect. As a result, Jorpes got interested in socialist ideas in the early 1910s. He joined the local Social Democratic student organization and wrote marxist articles to the ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digestion
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small molecules the body can use. In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix-turn-helix
Helix-turn-helix is a DNA-binding protein (DBP). The helix-turn-helix (HTH) is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression. It should not be confused with the helix–loop–helix motif. Discovery The discovery of the helix-turn-helix motif was based on similarities between several genes encoding transcription regulatory proteins from bacteriophage lambda and ''Escherichia coli'': Cro, CAP, and λ repressor, which were found to share a common 20–25 amino acid sequence that facilitates DNA recognition. Function The helix-turn-helix motif is a DNA-binding motif. The recognition and binding to DNA by helix-turn-helix proteins is done by the two α helices, one occupying the N-terminal end of the motif, the other at the C-terminus. In most cases, such as in the Cro repressor, the second ... [...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] |
Sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid. Spelling "Sulfate" is the spelling recommended by IUPAC, but "sulphate" was traditionally used in British English. Structure The sulfate anion consists of a central sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry is the same as that of methane. The sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the −2 state. The sulfate ion carries an overall charge of −2 and it is the conjugate base of the bisulfate (or hydrogensulfate) ion, , which is in turn the conjugate base of , sulfuric acid. Organic sulfate esters, such as dimethyl sulfate, are covalent compounds and esters of sulfuric acid. The tetrahedral molecular geometry of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post-translational Modification
Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribosomes translating mRNA into polypeptide chains, which may then undergo PTM to form the mature protein product. PTMs are important components in cell signaling, as for example when prohormones are converted to hormones. Post-translational modifications can occur on the amino acid side chains or at the protein's C- or N- termini. They can extend the chemical repertoire of the 20 standard amino acids by modifying an existing functional group or introducing a new one such as phosphate. Phosphorylation is a highly effective mechanism for regulating the activity of enzymes and is the most common post-translational modification. Many eukaryotic and prokaryotic proteins also have carbohydrate molecules attached to them in a process called glycosyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
