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Permease
The permeases are membrane transport proteins, a class of multipass transmembrane proteins that allow the diffusion of a specific molecule in or out of the cell in the direction of a concentration gradient, a form of facilitated diffusion. The permease binding is first step of translocation. LacY protein from Escherichia coli is an example of a permease. See also * Lactose permease * Beta-galactoside permease It was originally discovered in the 1930s by Joy Adames. It is a transporter protein that helps in various aspects of cellular life including DNA replication, translation of RNA, and diffusion. * Amino acid permease Amino acid permeases are membrane permeases involved in the transport of amino acids into the cell. A number of such proteins have been found to be evolutionary related. These proteins contain 12 transmembrane segments. See also *Amino acid tra ... A permease (porter) is a protein or protein complex that catalyzes a vectorial reaction, irrespective of whether ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid Permease
Amino acid permeases are membrane permeases involved in the transport of amino acids into the cell. A number of such proteins have been found to be evolutionary related. These proteins contain 12 transmembrane segments. See also *Amino acid transporter Human proteins containing this domain CIP1; SLC12A1; SLC12A2; SLC12A3; SLC12A4; SLC12A5; SLC12A6; SLC12A7; SLC12A8; SLC12A9; SLC7A1; SLC7A10; SLC7A11; SLC7A13; SLC7A14; SLC7A2; SLC7A3; SLC7A4; SLC7A5; SLC7A6; SLC7A7; SLC7A8; SLC7A9 b(0,+)-type amino acid transporter 1, also known as b(0,+)AT1, is a protein which in humans is encoded by the ''SLC7A9'' gene. Function This gene encodes a protein that belongs to a family of light subunits of amino acid transporters. This pro ...; References Protein domains Protein families Membrane proteins {{membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactose Permease
Lactose permease is a membrane protein which is a member of the major facilitator family, major facilitator superfamily. Lactose permease can be classified as a symporter, which uses the Electrochemical gradient#Proton gradients, proton gradient towards the cell to transport galactoside, β-galactosides such as lactose in the same direction into the cell. The protein has twelve transmembrane helix, transmembrane alpha-helices and its molecular weight is 45,000 Daltons. It exhibits an internal two-fold symmetry, relating the N-terminal six helices onto the C-terminal helices. It is encoded by the ''lacY'' gene in the lac operon, ''lac'' operon. The sugar lies in the hydrophilic core of the protein which is accessible from the periplasm. On binding, a large conformational change takes place which makes the sugar binding site accessible from the cytoplasm. Mechanism: hydronium ions from the outside of the cell binds to a carboxyl group on the enzyme that allows it to undergo a conf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facilitated Diffusion
Facilitated diffusion (also known as facilitated transport or passive-mediated transport) is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins. Being passive, facilitated transport does not directly require chemical energy from ATP hydrolysis in the transport step itself; rather, molecules and ions move down their concentration gradient reflecting its diffusive nature. Facilitated diffusion differs from simple diffusion in several ways. # the transport relies on molecular binding between the cargo and the membrane-embedded channel or carrier protein. # the rate of facilitated diffusion is saturable with respect to the concentration difference between the two phases; unlike free diffusion which is linear in the concentration difference. # the temperature dependence of facilitated transport is substantially different due to the presence of an activated bin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Transport Protein
A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion or active transport. The two main types of proteins involved in such transport are broadly categorized as either ''channels'' or ''carriers''. The solute carriers and atypical SLCs are secondary active or facilitative transporters in humans. Collectively membrane transporters and channels are known as the transportome. Transportomes govern cellular influx and efflux of not only ions and nutrients but drugs as well. Difference between channels and carriers A carrier is not open simultaneously to both the extracellular and intracellular environments. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concentration Gradient
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, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-galactoside Permease
A galactoside is a glycoside containing galactose. The H of the OH group on carbon-1 of galactose is replaced by an organic moiety. Depending on whether the glycosidic bond lies "above" or "below" the plane of the galactose molecule, galactosides are classified as α-galactosides or β-galactosides. A β-galactoside is a type of galactoside in which the glycosidic bond lies above the plane of the galactose residue. The most commonly recognized and used β-galactoside in biochemistry is lactose Lactose is a disaccharide sugar synthesized by galactose and glucose subunits and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from ' (gen. '), the Latin word for milk, plus the suffix '' - .... However, other chemicals, such as ONPG, are known, but these are typically synthesized for biochemical assays. Galactosides play significant roles in metabolic processes of many organisms and are hydrolyzed by a class of enzymes called ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transport Proteins
A transport protein (variously referred to as a transmembrane pump, transporter, escort protein, acid transport protein, cation transport protein, or anion transport protein) is a protein that serves the function of moving other materials within an organism. Transport proteins are vital to the growth and life of all living things. There are several different kinds of transport proteins. Carrier proteins are proteins involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane. Carrier proteins are integral membrane proteins; that is, they exist within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion (i.e., passive transport) or active transport. These mechanisms of movement are known as carrier-mediated transport. Each carrier protein is designed to recognize only one substance or one group of very similar substances. Research ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
