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Aquaporin
Aquaporins, also called water channels, are channel proteins from a larger family of major intrinsic proteins that form pores in the membrane of biological cells, mainly facilitating transport of water between cells. The cell membranes of a variety of different bacteria, fungi, animal and plant cells contain aquaporins through which water can flow more rapidly into and out of the cell than by diffusing through the phospholipid bilayer. Aquaporins have six membrane-spanning alpha helical domains with both carboxylic and amino terminals on the cytoplasmic side. Two hydrophobic loops contain conserved asparagine- proline-alanine ("NPA motif") which form a barrel surrounding a central pore-like region that contains additional protein density. Because aquaporins are usually always open and are prevalent in just about every cell type, this leads to a misconception that water readily passes through the cell membrane down its concentration gradient. Water can pass through the cell m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Major Intrinsic Proteins
Major intrinsic proteins comprise a large superfamily of transmembrane protein channels that are grouped together on the basis of homology. The MIP superfamily includes three subfamilies: aquaporins, aquaglyceroporins and S-aquaporins. # The aquaporins (AQPs) are water selective. # The aquaglyceroporins are permeable to water, but also to other small uncharged molecules such as glycerol. # The third subfamily, with little conserved amino acid sequences around the NPA boxes, include ' superaquaporins' (S-aquaporins). The phylogeny of insect MIP family channels has been published. Families There are two families that belong to thMIP Superfamily 1.A.8- The Major Intrinsic Protein (MIP) Family 1.A.16- The Formate-Nitrite Transporter (FNT) Family The Major Intrinsic Protein Family (TC# 1.A.8) The MIP family is large and diverse, possessing thousands of members that form transmembrane channels. These channel proteins function in transporting water, small carbohydrates (e.g., gly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuromyelitis Optica
Neuromyelitis optica spectrum disorders (NMOSD), including neuromyelitis optica (NMO), are autoimmune diseases characterized by acute inflammation of the optic nerve (optic neuritis, ON) and the spinal cord (myelitis). Episodes of ON and myelitis can be simultaneous or successive. A relapsing disease course is common, especially in untreated patients. In more than 80% of cases, NMO is caused by immunoglobulin G autoantibodies to aquaporin 4 ( anti-AQP4), the most abundant water channel protein in the central nervous system. A subset of anti-AQP4-negative cases is associated with antibodies against myelin oligodendrocyte glycoprotein ( anti-MOG). Rarely, NMO may occur in the context of other autoimmune diseases (e.g. connective tissue disorders, paraneoplastic syndromes) or infectious diseases. In some cases, the etiology remains unknown (idiopathic NMO). Multiple sclerosis (MS) and NMO can be similar in clinical and radiological presentation, and MS may very rarely present ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquaporin 1
Aquaporin 1 (AQP-1) is a protein that in humans is encoded by the ''AQP1'' gene. AQP-1 is a widely expressed water channel, whose physiological function has been most thoroughly characterized in the kidney. It is found in the basolateral and apical plasma membranes of the proximal tubules, the descending limb of the loop of Henle, and in the descending portion of the vasa recta. Additionally, it is found in red blood cells, vascular endothelium, the gastrointestinal tract, sweat glands, lungs, and the central nervous system. Neural AQP-1 receptors are regulated by vasopressin AVPR1A receptor activity. Function Aquaporins are a family of small integral membrane proteins related to the major intrinsic protein ( MIP or AQP0). This gene encodes an aquaporin which functions as both a molecular water channel protein and as a non-selective cation channel gated by cyclic guanosine monophosphate (cGMP). It is a homotetramer with six bilayer spanning domains and N-glycosylation s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Agre
Peter Agre (born January 30, 1949) is an American physician, Nobel Laureate, and molecular biologist, Bloomberg Distinguished Professor at the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins School of Medicine, and director of the Johns Hopkins Malaria Research Institute. In 2003, Agre and Roderick MacKinnon shared the 2003 Nobel Prize in Chemistry for "discoveries concerning channels in cell membranes." Agre was recognized for his discovery of aquaporin water channels. Aquaporins are water-channel proteins that move water molecules through the cell membrane. In 2009, Agre was elected president of the American Association for the Advancement of Science (AAAS) and became active in science diplomacy. Biography Agre is the second of six children born in Northfield, Minnesota to parents of Norwegian and Swedish descent. Agre is a Lutheran. Fascinated by international travel after a high school camping trip through the Soviet Union, Agre was an inconsistent stude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diabetes Insipidus
Diabetes insipidus (DI), recently renamed to Arginine Vasopressin Deficiency (AVP-D) and Arginine Vasopressin Resistance (AVP-R), is a condition characterized by large amounts of dilute urine and increased thirst. The amount of urine produced can be nearly 20 liters per day. Reduction of fluid has little effect on the concentration of the urine. Complications may include dehydration or seizures. There are four types of DI, each with a different set of causes. Central DI (CDI) is due to a lack of the hormone vasopressin (antidiuretic hormone). This can be due to injury to the hypothalamus or pituitary gland or genetics. Nephrogenic DI (NDI) occurs when the kidneys do not respond properly to vasopressin. Dipsogenic DI is a result of excessive fluid intake due to damage to the hypothalamic thirst mechanism. It occurs more often in those with certain psychiatric disorders or on certain medications. Gestational DI occurs only during pregnancy. Diagnosis is often based on urine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johns Hopkins University
Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consistently ranks among the most prestigious universities in the United States and the world. The university was named for its first benefactor, the American entrepreneur and Quaker philanthropist Johns Hopkins. Hopkins' $7 million bequest to establish the university was the largest philanthropic gift in U.S. history up to that time. Daniel Coit Gilman, who was inaugurated as Johns Hopkins's first president on February 22, 1876, led the university to revolutionize higher education in the U.S. by integrating teaching and research. In 1900, Johns Hopkins became a founding member of the American Association of Universities. The university has led all U.S. universities in annual research expenditures over the past three decades. Johns Hopkin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of cells and organelles, being selectively permeable to io ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmosis
Osmosis (, ) is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region of higher solute concentration), in the direction that tends to equalize the solute concentrations on the two sides. It may also be used to describe a physical process in which any solvent moves across a selectively permeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations. Osmosis can be made to do work. Osmotic pressure is defined as the external pressure required to be applied so that there is no net movement of solvent across the membrane. Osmotic pressure is a colligative property, meaning that the osmotic pressure depends on the molar concentration of the solute but not on its identity. Osmosis is a vital process in biological systems, as biological membranes are semipe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simple Diffusion
Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size (mass) of the particles. Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration. Once the concentrations are equal the molecules continue to move, but since there is no concentration gradient the process of molecular diffusion has ceased and is instead governed by the process of self-diffusion, originating from the random motion of the molecules. The result of diffusion is a gradual mixing of material such that the distribution of molecules is uniform. Since the molecules are still in motion, but an equilibrium has been established, the result of molecular diffusion is called a "dynamic equilibrium". In a phase with uniform temperature, absent external net forces acting on the particles, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercomputer
A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second ( FLOPS) instead of million instructions per second (MIPS). Since 2017, there have existed supercomputers which can perform over 1017 FLOPS (a hundred quadrillion FLOPS, 100 petaFLOPS or 100 PFLOPS). For comparison, a desktop computer has performance in the range of hundreds of gigaFLOPS (1011) to tens of teraFLOPS (1013). Since November 2017, all of the world's fastest 500 supercomputers run on Linux-based operating systems. Additional research is being conducted in the United States, the European Union, Taiwan, Japan, and China to build faster, more powerful and technologically superior exascale supercomputers. Supercomputers play an important role in the field of computational science, and are used for a wide range of computationally intensive tasks in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelial Cells
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of ep ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
