Thylakoid Membrane Proteins: Proteins found within the THYLAKOID MEMBRANES of photosynthetic organisms such as PLANTS and PHYTOPLANKTON. Many of the proteins in this class are involved in the process of PHOTOSYNTHESIS and the generation of ADENOSINE TRIPHOSPHATE.Thylakoids: Membranous cisternae of the CHLOROPLAST containing photosynthetic pigments, reaction centers, and the electron-transport chain. Each thylakoid consists of a flattened sac of membrane enclosing a narrow intra-thylakoid space (Lackie and Dow, Dictionary of Cell Biology, 2nd ed). Individual thylakoids are interconnected and tend to stack to form aggregates called grana. They are found in cyanobacteria and all plants.Endoplasmic Reticulum: A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)Chloroplasts: Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.Intracellular Membranes: Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Photosystem II Protein Complex: A large multisubunit protein complex found in the THYLAKOID MEMBRANE. It uses light energy derived from LIGHT-HARVESTING PROTEIN COMPLEXES to catalyze the splitting of WATER into DIOXYGEN and of reducing equivalents of HYDROGEN.Light-Harvesting Protein Complexes: Complexes containing CHLOROPHYLL and other photosensitive molecules. They serve to capture energy in the form of PHOTONS and are generally found as components of the PHOTOSYSTEM I PROTEIN COMPLEX or the PHOTOSYSTEM II PROTEIN COMPLEX.Photosynthetic Reaction Center Complex Proteins: Protein complexes that take part in the process of PHOTOSYNTHESIS. They are located within the THYLAKOID MEMBRANES of plant CHLOROPLASTS and a variety of structures in more primitive organisms. There are two major complexes involved in the photosynthetic process called PHOTOSYSTEM I and PHOTOSYSTEM II.Chloroplast Proteins: Proteins encoded by the CHLOROPLAST GENOME or proteins encoded by the nuclear genome that are imported to and resident in the CHOROPLASTS.Photosystem I Protein Complex: A large multisubunit protein complex that is found in the THYLAKOID MEMBRANE. It uses light energy derived from LIGHT-HARVESTING PROTEIN COMPLEXES to drive electron transfer reactions that result in either the reduction of NADP to NADPH or the transport of PROTONS across the membrane.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Chlorophyll: Porphyrin derivatives containing magnesium that act to convert light energy in photosynthetic organisms.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Cytochrome b6f Complex: A protein complex that includes CYTOCHROME B6 and CYTOCHROME F. It is found in the THYLAKOID MEMBRANE and plays an important role in process of PHOTOSYNTHESIS by transferring electrons from PLASTOQUINONE to PLASTOCYANIN or CYTOCHROME C6. The transfer of electrons is coupled to the transport of PROTONS across the membrane.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Membranes: Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Membrane Lipids: Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Mitochondrial Membranes: The two lipoprotein layers in the MITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Protein Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.Mitochondria: Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)Membrane Transport Proteins: Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.Arabidopsis Proteins: Proteins that originate from plants species belonging to the genus ARABIDOPSIS. The most intensely studied species of Arabidopsis, Arabidopsis thaliana, is commonly used in laboratory experiments.Spinacia oleracea: A widely cultivated plant, native to Asia, having succulent, edible leaves eaten as a vegetable. (From American Heritage Dictionary, 1982)Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Endoplasmic Reticulum Stress: Various physiological or molecular disturbances that impair ENDOPLASMIC RETICULUM function. It triggers many responses, including UNFOLDED PROTEIN RESPONSE, which may lead to APOPTOSIS; and AUTOPHAGY.Mitochondrial Membrane Transport Proteins: Proteins involved in the transport of specific substances across the membranes of the MITOCHONDRIA.Peas: A variable annual leguminous vine (Pisum sativum) that is cultivated for its rounded smooth or wrinkled edible protein-rich seeds, the seed of the pea, and the immature pods with their included seeds. (From Webster's New Collegiate Dictionary, 1973)Endoplasmic Reticulum, Rough: A type of endoplasmic reticulum (ER) where polyribosomes are present on the cytoplasmic surfaces of the ER membranes. This form of ER is prominent in cells specialized for protein secretion and its principal function is to segregate proteins destined for export or intracellular utilization.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Galactolipids: A group of GLYCOLIPIDS in which the sugar group is GALACTOSE. They are distinguished from GLYCOSPHINGOLIPIDS in lacking nitrogen. They constitute the majority of MEMBRANE LIPIDS in PLANTS.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Golgi Apparatus: A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough ENDOPLASMIC RETICULUM and directing them to secretory vesicles, LYSOSOMES, or the CELL MEMBRANE. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Mitochondrial Proteins: Proteins encoded by the mitochondrial genome or proteins encoded by the nuclear genome that are imported to and resident in the MITOCHONDRIA.Membranes, Artificial: Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.Protein Sorting Signals: Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Bacterial Outer Membrane Proteins: Proteins isolated from the outer membrane of Gram-negative bacteria.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Cyanobacteria: A phylum of oxygenic photosynthetic bacteria comprised of unicellular to multicellular bacteria possessing CHLOROPHYLL a and carrying out oxygenic PHOTOSYNTHESIS. Cyanobacteria are the only known organisms capable of fixing both CARBON DIOXIDE (in the presence of light) and NITROGEN. Cell morphology can include nitrogen-fixing heterocysts and/or resting cells called akinetes. Formerly called blue-green algae, cyanobacteria were traditionally treated as ALGAE.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Protein PrecursorsModels, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Cell Fractionation: Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.Membrane Fluidity: The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.Photosynthesis: The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)Erythrocyte Membrane: The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.Sarcoplasmic Reticulum: A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Bacterial Proteins: Proteins found in any species of bacterium.Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.Protein Processing, Post-Translational: Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.Kinetics: The rate dynamics in chemical or physical systems.Saccharomyces cerevisiae Proteins: Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Endoplasmic Reticulum, Smooth: A type of endoplasmic reticulum lacking associated ribosomes on the membrane surface. It exhibits a wide range of specialized metabolic functions including supplying enzymes for steroid synthesis, detoxification, and glycogen breakdown. In muscle cells, smooth endoplasmic reticulum is called SARCOPLASMIC RETICULUM.Electron Transport: The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Saccharomyces cerevisiae: A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Lipid Bilayers: Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.Synechocystis: A form-genus of unicellular CYANOBACTERIA in the order Chroococcales. None of the strains fix NITROGEN, there are no gas vacuoles, and sheath layers are never produced.Molecular Chaperones: A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures.Protein Folding: Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.Fabaceae: The large family of plants characterized by pods. Some are edible and some cause LATHYRISM or FAVISM and other forms of poisoning. Other species yield useful materials like gums from ACACIA and various LECTINS like PHYTOHEMAGGLUTININS from PHASEOLUS. Many of them harbor NITROGEN FIXATION bacteria on their roots. Many but not all species of "beans" belong to this family.Cytochromes f: Cytochromes f are found as components of the CYTOCHROME B6F COMPLEX. They play important role in the transfer of electrons from PHOTOSYSTEM I to PHOTOSYSTEM II.Chlamydomonas: A genus GREEN ALGAE in the order VOLVOCIDA. It consists of solitary biflagellated organisms common in fresh water and damp soil.Subcellular Fractions: Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)Molecular Weight: The sum of the weight of all the atoms in a molecule.Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Freeze Fracturing: Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.Plants, Medicinal: Plants whose roots, leaves, seeds, bark, or other constituent parts possess therapeutic, tonic, purgative, curative or other pharmacologic attributes, when administered to man or animals.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Mitochondria, Liver: Mitochondria in hepatocytes. As in all mitochondria, there are an outer membrane and an inner membrane, together creating two separate mitochondrial compartments: the internal matrix space and a much narrower intermembrane space. In the liver mitochondrion, an estimated 67% of the total mitochondrial proteins is located in the matrix. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p343-4)Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Detergents: Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Basement Membrane: A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Corneal Stroma: The lamellated connective tissue constituting the thickest layer of the cornea between the Bowman and Descemet membranes.Submitochondrial Particles: The various filaments, granules, tubules or other inclusions within mitochondria.Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Cytosol: Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.Plastoquinone: Polyunsaturated side-chain quinone derivative which is an important link in the electron transport chain of green plants during the photosynthetic conversion of light energy by photophosphorylation into the potential energy of chemical bonds.Plastocyanin: A copper-containing plant protein that is a fundamental link in the electron transport chain of green plants during the photosynthetic conversion of light energy by photophosphorylation into the potential energy of chemical bonds.Recombinant Proteins: Proteins prepared by recombinant DNA technology.L-Lactate Dehydrogenase (Cytochrome): A cytochrome form of lactate dehydrogenase found in the MITOCHONDRIA. It catalyzes the oxidation of L-lactate to PYRUVATE with transfer of electrons to CYTOCHROME C. The enzyme utilizes FMN and PROTOHEME IX as cofactors.Cytoplasm: The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Signal Recognition Particle: A cytosolic ribonucleoprotein complex that acts to induce elongation arrest of nascent presecretory and membrane proteins until the ribosome becomes associated with the rough endoplasmic reticulum. It consists of a 7S RNA and at least six polypeptide subunits (relative molecular masses 9, 14, 19, 54, 68, and 72K).Cytochromes b6: Cytochromes of the b group that are found as components of the CYTOCHROME B6F COMPLEX. They contain two non-covalently bound HEME B groups.Ear, Inner: The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.Microscopy, Confocal: A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.Photophosphorylation: The use of light to convert ADP to ATP without the concomitant reduction of dioxygen to water as occurs during OXIDATIVE PHOSPHORYLATION in MITOCHONDRIA.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Electron Transport Complex IV: A multisubunit enzyme complex containing CYTOCHROME A GROUP; CYTOCHROME A3; two copper atoms; and 13 different protein subunits. It is the terminal oxidase complex of the RESPIRATORY CHAIN and collects electrons that are transferred from the reduced CYTOCHROME C GROUP and donates them to molecular OXYGEN, which is then reduced to water. The redox reaction is simultaneously coupled to the transport of PROTONS across the inner mitochondrial membrane.Liposomes: Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.Cell Compartmentation: A partitioning within cells due to the selectively permeable membranes which enclose each of the separate parts, e.g., mitochondria, lysosomes, etc.Microsomes: Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Blotting, Western: Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.Solubility: The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Nigericin: A polyether antibiotic which affects ion transport and ATPase activity in mitochondria. It is produced by Streptomyces hygroscopicus. (From Merck Index, 11th ed)Organelles: Specific particles of membrane-bound organized living substances present in eukaryotic cells, such as the MITOCHONDRIA; the GOLGI APPARATUS; ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.Unfolded Protein Response: A cellular response to environmental insults that cause disruptions in PROTEIN FOLDING and/or accumulation of defectively folded protein in the ENDOPLASMIC RETICULUM. It consists of a group of regulatory cascades that are triggered as a response to altered levels of calcium and/or the redox state of the endoplasmic reticulum. Persistent activation of the unfolded protein response leads to the induction of APOPTOSIS.Chlorophyta: A phylum of photosynthetic EUKARYOTA bearing double membrane-bound plastids containing chlorophyll a and b. They comprise the classical green algae, and represent over 7000 species that live in a variety of primarily aquatic habitats. Only about ten percent are marine species, most live in freshwater.Fungal Proteins: Proteins found in any species of fungus.Immunoblotting: Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Porins: Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES.Chloroplast Proton-Translocating ATPases: Proton-translocating ATPases which produce ADENOSINE TRIPHOSPHATE in plants. They derive energy from light-driven reactions that develop high concentrations of protons within the membranous cisternae (THYLAKOIDS) of the CHLOROPLASTS.Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Mesophyll Cells: Large and highly vacuolated cells possessing many chloroplasts occuring in the interior cross-section of leaves, juxtaposed between the epidermal layers.Glycosylation: The chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins. Glycosyl transferases are used in this biochemical reaction.Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Brefeldin A: A fungal metabolite which is a macrocyclic lactone exhibiting a wide range of antibiotic activity.HeLa Cells: The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Electron Microscope Tomography: A tomographic technique for obtaining 3-dimensional images with transmission electron microscopy.Tunicamycin: An N-acetylglycosamine containing antiviral antibiotic obtained from Streptomyces lysosuperificus. It is also active against some bacteria and fungi, because it inhibits the glucosylation of proteins. Tunicamycin is used as tool in the study of microbial biosynthetic mechanisms.Heat-Shock Proteins: Proteins which are synthesized in eukaryotic organisms and bacteria in response to hyperthermia and other environmental stresses. They increase thermal tolerance and perform functions essential to cell survival under these conditions.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Proton-Translocating ATPases: Multisubunit enzymes that reversibly synthesize ADENOSINE TRIPHOSPHATE. They are coupled to the transport of protons across a membrane.Plastids: Self-replicating cytoplasmic organelles of plant and algal cells that contain pigments and may synthesize and accumulate various substances. PLASTID GENOMES are used in phylogenetic studies.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Xanthophylls: Oxygenated forms of carotenoids. They are usually derived from alpha and beta carotene.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Calnexin: A lectin found in ENDOPLASMIC RETICULUM membranes that binds to specific N-linked OLIGOSACCHARIDES found on newly synthesized proteins. It may play role in PROTEIN FOLDING or retention and degradation of misfolded proteins in the endoplasmic reticulum.Microscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Transfection: The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Mitochondrial ADP, ATP Translocases: A class of nucleotide translocases found abundantly in mitochondria that function as integral components of the inner mitochondrial membrane. They facilitate the exchange of ADP and ATP between the cytosol and the mitochondria, thereby linking the subcellular compartments of ATP production to those of ATP utilization.Sarcoplasmic Reticulum Calcium-Transporting ATPases: Calcium-transporting ATPases that catalyze the active transport of CALCIUM into the SARCOPLASMIC RETICULUM vesicles from the CYTOPLASM. They are primarily found in MUSCLE CELLS and play a role in the relaxation of MUSCLES.ATP-Dependent Proteases: Proteases that contain proteolytic core domains and ATPase-containing regulatory domains. They are usually comprised of large multi-subunit assemblies. The domains can occur within a single peptide chain or on distinct subunits.Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Fluorescence: The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.Macromolecular Substances: Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.Adenosine Triphosphatases: A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.Apoptosis: One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.Mutagenesis, Site-Directed: Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Calcium-Transporting ATPases: Cation-transporting proteins that utilize the energy of ATP hydrolysis for the transport of CALCIUM. They differ from CALCIUM CHANNELS which allow calcium to pass through a membrane without the use of energy.Membrane Potential, Mitochondrial: The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.Darkness: The absence of light.Thapsigargin: A sesquiterpene lactone found in roots of THAPSIA. It inhibits CA(2+)-TRANSPORTING ATPASE mediated uptake of CALCIUM into SARCOPLASMIC RETICULUM.Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Calreticulin: A multifunctional protein that is found primarily within membrane-bound organelles. In the ENDOPLASMIC RETICULUM it binds to specific N-linked oligosaccharides found on newly-synthesized proteins and functions as a MOLECULAR CHAPERONE that may play a role in PROTEIN FOLDING or retention and degradation of misfolded proteins. In addition calreticulin is a major storage form for CALCIUM and functions as a calcium-signaling molecule that can regulate intracellular calcium HOMEOSTASIS.Oxidoreductases: The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)COS Cells: CELL LINES derived from the CV-1 cell line by transformation with a replication origin defective mutant of SV40 VIRUS, which codes for wild type large T antigen (ANTIGENS, POLYOMAVIRUS TRANSFORMING). They are used for transfection and cloning. (The CV-1 cell line was derived from the kidney of an adult male African green monkey (CERCOPITHECUS AETHIOPS).)DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Transcription Factor CHOP: A CCAAT-enhancer binding protein that is induced by DNA DAMAGE and growth arrest. It serves as a dominant negative inhibitor of other CCAAT-enhancer binding proteins.Digitonin: A glycoside obtained from Digitalis purpurea; the aglycone is digitogenin which is bound to five sugars. Digitonin solubilizes lipids, especially in membranes and is used as a tool in cellular biochemistry, and reagent for precipitating cholesterol. It has no cardiac effects.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Cytochromes c1: The 30-kDa membrane-bound c-type cytochrome protein of mitochondria that functions as an electron donor to CYTOCHROME C GROUP in the mitochondrial and bacterial RESPIRATORY CHAIN. (From Enzyme Nomenclature, 1992, p545)Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Phycobilisomes: Light energy harvesting structures attached to the THYLAKOID MEMBRANES of CYANOBACTERIA and RED ALGAE. These multiprotein complexes contain pigments (PHYCOBILIPROTEINS) that transfer light energy to chlorophyll a.Phosphatidylglycerols: A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis.Centrifugation, Density Gradient: Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Pigments, Biological: Any normal or abnormal coloring matter in PLANTS; ANIMALS or micro-organisms.Cytochromes: Hemeproteins whose characteristic mode of action involves transfer of reducing equivalents which are associated with a reversible change in oxidation state of the prosthetic group. Formally, this redox change involves a single-electron, reversible equilibrium between the Fe(II) and Fe(III) states of the central iron atom (From Enzyme Nomenclature, 1992, p539). The various cytochrome subclasses are organized by the type of HEME and by the wavelength range of their reduced alpha-absorption bands.Phosphatidylcholines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Endopeptidases: A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.Calcium-Binding Proteins: Proteins to which calcium ions are bound. They can act as transport proteins, regulator proteins, or activator proteins. They typically contain EF HAND MOTIFS.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Periplasm: The space between the inner and outer membranes of a cell that is shared with the cell wall.Nuclear Envelope: The membrane system of the CELL NUCLEUS that surrounds the nucleoplasm. It consists of two concentric membranes separated by the perinuclear space. The structures of the envelope where it opens to the cytoplasm are called the nuclear pores (NUCLEAR PORE).Cytochromes c: Cytochromes of the c type that are found in eukaryotic MITOCHONDRIA. They serve as redox intermediates that accept electrons from MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX III and transfer them to MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX IV.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Proton-Motive Force: Energy that is generated by the transfer of protons or electrons across an energy-transducing membrane and that can be used for chemical, osmotic, or mechanical work. Proton-motive force can be generated by a variety of phenomena including the operation of an electron transport chain, illumination of a PURPLE MEMBRANE, and the hydrolysis of ATP by a proton ATPase. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed, p171)Cardiolipins: Acidic phospholipids composed of two molecules of phosphatidic acid covalently linked to a molecule of glycerol. They occur primarily in mitochondrial inner membranes and in bacterial plasma membranes. They are the main antigenic components of the Wassermann-type antigen that is used in nontreponemal SYPHILIS SERODIAGNOSIS.Chlamydomonas reinhardtii: A species of GREEN ALGAE. Delicate, hairlike appendages arise from the flagellar surface in these organisms.Trypsin: A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC 3.4.21.4.Cross-Linking Reagents: Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other.Oxidoreductases Acting on Sulfur Group Donors: Oxidoreductases with specificity for oxidation or reduction of SULFUR COMPOUNDS.Gene Deletion: A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.Amino Acid Motifs: Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
Most proteins that are secretory, membrane-bound, or reside in the endoplasmic reticulum (ER), golgi or endosomes use the co- ... In the stroma the stromal import sequence is cleaved off and folded as well as intra-chloroplast sorting to thylakoids ... Targeting to the outer membrane, intermembrane space, and inner membrane often requires another signal sequence in addition to ... Targeting signals are the pieces of information that enable the cellular transport machinery to correctly position a protein ...
They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum. The fact that ... 1 Granum 2 Chloroplast envelope 2.1 Outer membrane 2.2 Intermembrane space 2.3 Inner membrane 3 Thylakoid 3.1 Thylakoid space ( ... From here, chloroplast proteins bound for the stroma must pass through two protein complexes-the TOC complex, or translocon on ... and not the phagosomal membrane from the host, which was probably lost. The new cellular resident quickly became an advantage, ...
They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum.[14] The fact that ... Stroma. Main article: Stroma. The protein-rich,[33] alkaline,[101] aqueous fluid within the inner chloroplast membrane and ... a double membrane with an intermembrane space and phycobilin pigments organized into phycobilisomes on the thylakoid membranes ... and not the phagosomal membrane from the host, which was probably lost.[16] The new cellular resident quickly became an ...
Thylakoids are membrane-bound structures embedded in the chloroplast stroma. A stack of thylakoids is called a granum and ... the endoplasmic reticulum and inner membrane of the plastid envelope and transported from the inner membrane to the thylakoids ... 2.2 Intermembrane space. 2.3 Inner membrane. 3 Thylakoid ◄ You are here. 3.1 Thylakoid space (lumen). 3.2 Thylakoid membrane. 4 ... Integral membrane proteinsEdit. Thylakoid membranes contain integral membrane proteins which play an important role in light ...
마운틴코아티속(Nasua)은 아메리카너구리과에 속하는 포유류 속의 하나로 2종으로 이루어져 있다. 코아티속에 속하는 대형 코아티와 달리, 마운틴코아티는 몸구게사 1~1.5kg에 불과하며 남아메리카 안데스 산맥 북부 지역의 고지대에서 발견된다.[1][2] 최근까지는 단일종 아래에 3종의 아종으로 이루어져 있었다.[3] 2009년에 베네수엘라에서 서식하는 동부마운틴코아티와 콜롬비아, 에콰도르에서 발견되는 서부마운틴코아티(아종 quitensis 포함)의 2종으로 분리되었다.[4] 페루 남부에서 발견된 일군의 개체군(이전의 분포 한계보다 남쪽으로 1000km 이상 떨어져 있다.)은 임시로 서부마운틴코아티로 명명했지만, 미기록종일 수도 있다.[5] 겉모습에서 마운틴코아티 2종은 꽤 닮았지만, 동부마운틴코아티가 전체적으로 작으며, 평균보다 다소 작은 꼬리를 갖고 있으며, ...
The red algae form a distinct group characterized by having eukaryotic cells without flagella and centrioles, chloroplasts that lack external endoplasmic reticulum and contain unstacked (stroma) thylakoids, and use phycobiliproteins as accessory pigments, which give them their red color.[8] Red algae store sugars as floridean starch, which is a type of starch that consists of highly branched amylopectin without amylose,[9] as food reserves outside their plastids. Most red algae are also multicellular, macroscopic, marine, and reproduce sexually. The red algal life history is typically an alternation of generations that may have three generations rather than two.[10]. Chloroplasts evolved following an endosymbiotic event between an ancestral, photosynthetic cyanobacterium and an early eukarytoic phagotroph.[11] This event (termed primary endosymbiosis) resulted in the origin of the red and green algae, and ...
Hloroplasti se razvijaju iz proplastida kada klica biljke izbija iz zemlje. Za formiranje tilakoida neophodna je svjetlost. U embrionu biljke i u nedostatku svjetlosti, proplastidi se razvijaju u etioplaste koje sadrže polukristalne membranske strukture zvane prolamelarna tijela. Kada se ona izlože svjetlosti razvijaju se u tilakoide. Ovo se ne dešava kada klica raste u mraku, jer se tada dešava etiolacija. Nedostatak svjetlosti može izazvati odumiranje tilakoida. Ovo dalje uzrokuje odumiranje cijelog hloroplasta i vodi ka uginuću biljke.. Formiranje tilakoida zahtjeva akciju VIPP1 (bjelančevine u plastidima koje induciraju vesikule). Biljke ne mogu opstati bez ove bjelančevine a smanjen nivo VIPP1 može dovesti do usporavanja rasta i svjetlijih biljaka sa umanjenom mogućnošću fotosinteze. Smatra se da je VIPP1 neophodan za osnovno formiranje membrane tilakoida ali ne i za sastavljanje bjelančevinastih kompleksa u membrani.[7]Ona je konzervirana u svim organizmima koji sadrže ...
Eudikotiledone ili eudikotide su monofiletska grana cvetnica koje su ranije označavane kao trikolpate ili nemagnolidne dikotiledone. Ovaj botanički termin su prvi uveli evolucijski botaničar James A. Doyle i paleobotaničar Carol L. HottonHotton, 1991, da bi naglasili kasniju evolucijsku divergenciju trikolpatnih dikotiledona od ranijih, manje specijaliziranih, dikotiledona.[1]. Bliski odnosi među cvetnica sa trikolplatnim polenom su prvobitno viđeni u morfološkim studijama zajedničkih izvedenih svojstava. Ove biljke imaju izrazitu zajedničku osobinu u polenovim zrnima sa tri pločice ili žleba, paralelnim sa polarnom osom. Kasniji molekulsko-biološki dokazi su potvrdili genetičku osnovu za evolucijske odnosa među cvetnicama sa trobridim polenom i dva kotiledona. Termin znači "prave dikodiledone", jer obuhvataju većinu biljaka koje su uključene u dvokotiledone i imaju fenotipska obilježja dikotiledona. Izraz "eudikotile(done)" je naknadno široko usvojen u botanici da se imenuje ...
ER retention refers to proteins that are retained in the endoplasmic reticulum, or ER, after folding; these are known as ER resident proteins. Their localization to the ER often depends on certain sequences of amino acids located at the N-terminus or C-terminus. The classical ER retention signal is the C-terminal KDEL sequence for lumen bound proteins and KKXX for transmembrane localization. These signals allow for retrieval from the Golgi apparatus by ER retention receptors, effectively maintaining the protein in the ER.[1] Other mechanisms for ER retention are being studied but are not as well characterized as signal retention. ...
GPI transamidase component PIG-T is an enzyme that in humans is encoded by the PIGT gene. This gene encodes a protein that is involved in glycosylphosphatidylinositol (GPI)-anchor biosynthesis. The GPI-anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. This protein is an essential component of the multisubunit enzyme, GPI transamidase. GPI transamidase mediates GPI anchoring in the endoplasmic reticulum, by catalyzing the transfer of fully assembled GPI units to proteins. PIGT has been shown to interact with PIGK and GPAA1. GRCh38: Ensembl release 89: ENSG00000124155 - Ensembl, May 2017 GRCm38: Ensembl release 89: ENSMUSG00000017721 - Ensembl, May 2017 "Human PubMed Reference:". "Mouse PubMed Reference:". Vainauskas S, Menon AK (Apr 2005). "Endoplasmic reticulum localization of Gaa1 and PIG-T, subunits of the glycosylphosphatidylinositol transamidase complex". ...
... , also designated as STIMATE (for STIM-activating enhancer), is an ER-resident multi-transmembrane protein identified through a proteomic study on the ER-PM junctions. The ER-PM junctions are defined as specialized junctional sites, also known as membrane contact sites, that connect the endoplasmic reticulum (ER) and the plasma membrane (PM), and are closely implicated in controlling lipid and calcium homeostasis in mammalian cells. TMEM110 is a positive modulator of calcium flux mediated by the STIM-ORAI signaling in vertebrates. STIMATE can physically associate with STIM1 to promote conformational switch of STIM1 from inactive toward an activated state, thereby coupling to and gating the ORAI calcium channels on the plasma membrane. Depletion of TMEM110 with RNAi knockdown or Cas9-mediated gene disruption substantially reduces the ...
Eukaryotic cells, including human cells, have a highly evolved process of secretion. Proteins targeted for the outside are synthesized by ribosomes docked to the rough endoplasmic reticulum (ER). As they are synthesized, these proteins translocate into the ER lumen, where they are glycosylated and where molecular chaperones aid protein folding. Misfolded proteins are usually identified here and retrotranslocated by ER-associated degradation to the cytosol, where they are degraded by a proteasome. The vesicles containing the properly folded proteins then enter the Golgi apparatus. In the Golgi apparatus, the glycosylation of the proteins is modified and further posttranslational modifications, including cleavage and functionalization, may occur. The proteins are then moved into secretory vesicles which travel along the cytoskeleton to the edge of the cell. More modification ...
The endoplasmic reticulum (ER) is a teep o organelle in the cells o eukaryotic organisms that forms an interconnectit network o flattened, membrane-enclosed sacs or tubes kent as cisternae. ...
The endoplasmic reticulum (ER) is a membranous synthesis and transport organelle that is an extension of the nuclear envelope. More than half the total membrane in eukaryotic cells is accounted for by the ER. The ER is made up of flattened sacs and branching tubules that are thought to interconnect, so that the ER membrane forms a continuous sheet enclosing a single internal space. This highly convoluted space is called the ER lumen and is also referred to as the ER cisternal space. The lumen takes up about ten percent of the entire cell volume. The endoplasmic reticulum membrane allows molecules to be selectively transferred between the lumen and the cytoplasm, and since it is connected to the nuclear envelope, it provides a channel between the nucleus and the cytoplasm.[23] The ER has a central role in producing, processing, and ...
OST is a component of the translocon in the endoplasmic reticulum (ER) membrane. A lipid-linked core-oligosaccharide is assembled at the membrane of the endoplasmic reticulum and transferred to selected asparagine residues of nascent polypeptide chains by the oligosaccharyl transferase complex.[3] The active site of OST is located about 4 nm from the lumenal face of the ER membrane.[4] It usually acts during translation as the nascent protein is entering the ER, but this cotranslational glycosylation is nevertheless called a posttranslational modification. A few examples have been found of OST activity after translation is complete.[5][6] Current opinion is that post-translational activity may occur if the protein is poorly folded or folds slowly.[6] ...
... is a protein in the endoplasmic reticulum in the cell. It comes in several different molecular masses, including: Grp78 (78 kDa) Grp94 (94 kDa) Grp170 (170 kDa), which is a human chaperone protein Henney CS (1979). "The "triggering" of cytotoxic cell differentiation in secondary cultures by subcellular antigens". J. Immunol. 122 (5): 2134. PMID 312858 ...
Junctophilin 2, also known as JPH2, is a protein which in humans is encoded by the JPH2 gene. Alternative splicing has been observed at this locus and two variants encoding distinct isoforms are described. Junctional complexes between the plasma membrane and endoplasmic/sarcoplasmic reticulum are a common feature of all excitable cell types and mediate cross talk between cell surface and intracellular ion channels. The protein encoded by this gene is a component of junctional complexes and is composed of a C-terminal hydrophobic segment spanning the endoplasmic/sarcoplasmic reticulum membrane and a remaining cytoplasmic membrane occupation and recognition nexus (MORN) domain that shows specific affinity for the plasma membrane. JPH2 is a member of the junctophilin gene family (the other ...
Ribosomes are attached to some of the membranes of the endoplasmic reticulum. These are the site of intensive protein synthesis ... The thylakoid vesicles are stacked to form structures called grana, which are separated by a space called the stroma. Within ... Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and usually lack membrane-bound organelles ( ... Protein comprises approximately 50% of cellular dry weight.. ..... Click the link for more information. as their main ...
Most proteins that are secretory, membrane-bound, or reside in the endoplasmic reticulum (ER), golgi or endosomes use the co- ... In the stroma the stromal import sequence is cleaved off and folded as well as intra-chloroplast sorting to thylakoids ... Targeting to the outer membrane, intermembrane space, and inner membrane often requires another signal sequence in addition to ... Targeting signals are the pieces of information that enable the cellular transport machinery to correctly position a protein ...
The rough endoplasmic reticulum contains membrane-bound 80S ribosomes that synthesize proteins destined for the cell membrane. ... the inner membrane, and the thylakoid membrane system. Inside the outer and inner membranes is the chloroplast stroma, a gel- ... Mitochondria are the site of cellular respiration. They have two membranes: an outer membrane and an inner membrane with ... the inner of which is extensively folded into cristae and is the site of the intermembrane space. The mitochondrial matrix ...
TGD4 Involved in Endoplasmic Reticulum-to-chloroplast Lipid Trafficking is a Phosphatidic Acid Binding Protein The Plant ... the chloroplast inner and outer envelope membranes, and the endoplasmic reticulum is emerging. Studies of thylakoid biogenesis ... Feb, 2012 , Pubmed ID: 22337920 Membrane transporters play a central role in many cellular processes that rely on the movement ... whereas the C-terminal domain faces the intermembrane space. It was previously shown that the C-terminal domain of TGD2 binds ...
double membrane. *stroma - contains ribosomes, lipid, circular DNA, starch grains. *thylakoids - flattened sacs in stroma ... Nuceloplasm - contains chromatin and coils of DNA bound to histone protein. *Nucleolus - produces RNA to make ribosomes ... Endoplasmic Reticulum (ER). *double membrane forming flattened sacs. *fluid filled spaces between called cisternae ... double membrane - seperated by intermembrane space. *inner membrane folded inwards to form cristae ...
... cellular power plant. Each mitochondrion is enclosed in a... ... is also associated with the smooth endoplasmic reticulum. ... Mitochondria Structure: Cristae, Matrix and Inner & Outer Membrane 3:47 * Chloroplast Structure: Chlorophyll, Stroma, Thylakoid ... Membrane-Bound Organelles in Eukaryotic Cells 4:39 * Membrane Proteins: Functions, Types & Structure 5:12 ... The Inter-membrane Space. The outer membrane creates the inter-membrane space between the outer and inner membranes. This space ...
They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum. The fact that ... 1 Granum 2 Chloroplast envelope 2.1 Outer membrane 2.2 Intermembrane space 2.3 Inner membrane 3 Thylakoid 3.1 Thylakoid space ( ... From here, chloroplast proteins bound for the stroma must pass through two protein complexes-the TOC complex, or translocon on ... and not the phagosomal membrane from the host, which was probably lost. The new cellular resident quickly became an advantage, ...
Bound ribosomes = Ribosomes attached to the outside of the endoplasmic reticulum. Generally make proteins that are destined for ... The thylakoid membrane segregates the interior of the chloroplast into two compartments: thylakoid space and stroma. Thylakoids ... A narrow intermembrane space separates the two membranes. b. Thylakoid space Thylakoids form another membranous system within ... Overview of an animal cell Overview of a plant cell The nucleus and its envelope Nucleus = membrane-bound cellular organelle in ...
thylakoid system, starch granules, and other proteins. are found floating around the stroma.. Thylakoid System. The thylakoid ... outer membrane is not permeable to. larger proteins.. Intermembrane Space. • This is usually a thin intermembrane. space ... Endoplasmic Reticulum Modifies protein and NO YES YES. lipids. Golgi Apparatus Modifies, sorts, tags, NO YES YES. packages, and ... cellular component. • Vesicles- smaller, can fuse with the plasma membrane or the other. membrane systems. CENTROSOME. • ...
In addition, eukaryotic cells tend to be larger and have a variety of membrane-bound organelles that perform specific, ... including a nucleus with a double membrane that encloses DNA. ... to the rough endoplasmic reticulum where they perform protein ... The chloroplast has an outer membrane, an inner membrane, and membrane structures called thylakoids that are stacked into grana ... The space between the two membranes is called the intermembrane space, and the space inside the inner membrane is called the ...
Thus, plastids are surrounded by double composite membranes with intermembrane spaces, have their own DNA, and are involved in ... Acrosome , Chloroplast , Cilium/Flagellum , Centriole , Endoplasmic reticulum , Golgi apparatus , Lysosome , Melanosome , ... contain stroma and grana thylakoids. The glaucocystophycean plastid, in contrast to the chloroplasts and the rhodoplasts, is ... The developing plastid has many nucleoids, localized at the periphery of the plastid, bound to the inner envelope membrane. ...
barbiturates Bottom This diagram Bound ribosomes calcium ions carbohydrate cell motility cells compartmental cellular ... internal compartment lipids liver cell lumen lysosomal storage diseases lysosome fusing matrix membrane proteins membranes ... c steroids stroma sugar suggested answers thylakoids tonoplast trans face Transport vesicles bud tubules tubulin vacuole ... cation enzymes digest drugs electron micrograph enclosed endomembrane system endoplasmic reticulum engul﫿ng eukaryotic cells ...
... thylakoids: inner membrane folds in disc- shapes: 1 stack of discs = granum  fluid in inner folds = stroma Plastids  group of ... of membrane in a cell  "endoplasmic" means within the cytoplasm"  "reticulum" means little net  made of network of tubules ... plasma membranes of adjacent cells tightly pressed against each other  bound together by proteins  form continuous seal ... intermembrane space & matrix)  matrix contains enzymes for cellular respiration, DNA, ribosomes  intermembrane has enzymes ...
... distinct inner and outer membranes, The location of ATPase, DNA and ribosomes The ... MITOCHONDRIA LECTURES OVERVIEW Mitochondrial Structure The arrangement of membranes: ... c. Endoplasmic reticulum. d. Space between inner and outer mitochondrial membranes e. Thylakoid membranes 17. ATP synthase can ... stroma c) intermembrane space d) matrix e) periplasm 6. Porins may be found: a) in the outer membrane of gram-negative bacteria ...
A regulatory mechanism linking thylakoid-bound ascorbate peroxidase action with ... and redox-associated proteins providing reactive oxygen species scavenging generated by electron transport chains functioning ... with the exception of plastid targeted specific antioxidant gene products such as thylakoid-bound ascorbate peroxidase, ... Genes related to thylakoid function were down-regulated as expected, ...
They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum.[14] The fact that ... Stroma. Main article: Stroma. The protein-rich,[33] alkaline,[101] aqueous fluid within the inner chloroplast membrane and ... a double membrane with an intermembrane space and phycobilin pigments organized into phycobilisomes on the thylakoid membranes ... and not the phagosomal membrane from the host, which was probably lost.[16] The new cellular resident quickly became an ...
... a lipid-raft protein, was also recently found to localize to PD (13). Several additional potential membrane-bound PD-localized ... by the plasma membranes of the cells it connects and contains at its axial center strands of the endoplasmic reticulum (ER) ... thaliana embryos contain fewer thylakoid membranes arranged in grana compared with WT embryos (Fig. 2 A and B). To investigate ... 5). These NDBs oxidize intermembrane NADH to reduce ubiquinone (UQ) to UQH2, which is, in turn, oxidized by AOX1a to reduce ...
The systematic analysis of the serine protease-like proteins in the two plant species has provided some insight into the ... we identified a very similar number of serine protease-like proteins in the two plant species (206 and 222, respectively). ... possible functional associations of previously uncharacterised serine protease-like proteins. Further investigation of these ... genome sequences has permitted the identification and comparison of the repertoire of serine protease-like proteins in the two ...
Thylakoids are membrane-bound structures embedded in the chloroplast stroma. A stack of thylakoids is called a granum and ... the endoplasmic reticulum and inner membrane of the plastid envelope and transported from the inner membrane to the thylakoids ... 2.2 Intermembrane space. 2.3 Inner membrane. 3 Thylakoid ◄ You are here. 3.1 Thylakoid space (lumen). 3.2 Thylakoid membrane. 4 ... Integral membrane proteinsEdit. Thylakoid membranes contain integral membrane proteins which play an important role in light ...
are characterized by numerous membrane-bound organelles. such as the endoplasmic reticulum, Golgi apparatus, chloroplasts, ... are the cellular structures responsible for protein synthesis. When viewed through an electron microscope, ribosomes appear ... Figure 10. The chloroplast has an outer membrane, an inner membrane, and membrane structures called thylakoids that are stacked ... The space between the two membranes is called the intermembrane space, and the space inside the inner membrane is called the ...
... proteins.The proteins move from the endoplasmic reticulum to the Golgi apparatus where they are packed into membrane bound ... the inter membrane space and the mitochondrial matrix. The intermembrane space is the narrow part between the two membranes ... is a membrane-bound sac that plays roles in intracellular digestion and the release of cellular waste products. In animal cells ... The light dependent reactions of photosynthesis take place at specialised cell membranes,such as Thylakoid membrane inside ...
Endoplasmic reticulum and Golgi apparatus in hepatocytes produce plasma proteins.. *The liver intercepts blood from the gut to ... Binding of hormones to membrane receptors activates a cascade mediated by a second messenger inside the cell. ... Light-dependent reactions take place in the intermembrane space of the thylakoids. ... Multicellular organisms have properties that emerge from the interaction of their cellular components. ...
... protein folding; LOCATED IN: integral to membrane, endoplasmic reticulum; EXPRESSED IN: 24 plant structures; EXPRESSED DURING: ... protein binding, zinc ion binding; INVOLVED IN: intracellular signaling cascade; LOCATED IN: cellular_component unknown; ... chloroplast thylakoid membrane, chloroplast; Has 18 Blast hits to 18 proteins in 7 species: Archae - 0; Bacteria - 0; Metazoa ... nucleoside diphosphate kinase 3 (ndpk3), located to the inter-membrane space in mitochondria ...
Endoplasmic reticulum: "a network of biological membranes inside the cytoplasm of a cell, some of which may have ribosomes ... Internal thylakoid membranes contain chlorophyll where photosynthesis takes place. [e] * Chloroplast membrane: Add brief ... Golgi apparatus: An organelle in eukaryotic cells that modifies many proteins and lipids from the endoplasmic reticulum; it is ... Cellular differentiation: Add brief definition or description * cellular respiration: A series of metabolic processes by which ...
... a membrane-bound nucleus; 2) numerous membrane-bound organelles such as the endoplasmic reticulum, Golgi apparatus, ... cellular structure that carries out protein synthesis. vacuole. membrane-bound sac, somewhat larger than a vesicle, which ... while chloroplasts have chlorophyll and accessory pigments in the thylakoids that form stacks (grana) and a stroma. ... The space between the two membranes is called the intermembrane space, and the space inside the inner membrane is called the ...
  • The plasma membranes of cells that specialize in absorption are folded into fingerlike projections called microvilli (singular = microvillus). (imedecin.com)
  • Tight Junctions  plasma membranes of adjacent cells tightly pressed against each other  bound together by proteins  form continuous seal around cell  example: tight jcts around skin cells make skin water proof Tight Junctions Cell Junctions in Animal Cells  2. (slidegur.com)
  • Each channel, or plasmodesma, is delimited by the plasma membranes of the cells it connects and contains at its axial center strands of the endoplasmic reticulum (ER) that are continuous between cells. (pnas.org)
  • cell motility Cytoskeleton & Cell Motility  involves interaction between cytoskeleton & motor proteins  both work with plasma membrane to move cell  make flagella or cilia move  muscle fiber contraction  migration of neurotransmitter vesicles to axon tips Motor Protein Animation  http://www.sinauer.com/cooper5e/animation1204. (slidegur.com)
  • made of DNA (see nucleic acid nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis. (thefreedictionary.com)
  • Eukaryotic cells compensate for the small surface area to volume ratio by having internal membrane which: Partition the cell into compartments. (studyres.com)
  • html Cytoskeleton Animation  http://www.bmc.med.utoronto.ca/bmc/images/stori es/videos/eddy_xuan.mov Microtubules  in all eukaryotic cells  hollow rods 25 nm across, 200 nm - 25 microns long  made from a globular protein: tubulin, a dimer (made of 2 subunits) Microtubules Assembly of Microtubules  http://www.sinauer.com/cooper5e/animation1203. (slidegur.com)
  • Plant cells are bound by cellulosic cell walls, creating a challenge to resource sharing and information exchange among individual cells. (pnas.org)
  • The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. (prepscholar.com)
  • Chromosomes, each consisting of a linear DNA molecule coiled around basic (alkaline) proteins called histones. (libretexts.org)
  • Seven transmembrane G-protein coupled receptors (which represent about 5% of the genes in humans) mostly do not have an amino-terminal signal sequence. (wikipedia.org)
  • PD also contain cytoskeleton-associated proteins, including actin ( 7 ) and myosin ( 8 ). (pnas.org)
  • The transition from active growth to dormancy in woody perennials of the temperate and boreal regions involves molecular, cellular, and whole-plant responses. (biomedcentral.com)
  • Substantial changes in the transcriptome and metabolome accompany this transition and enable the plant to avoid cellular damage resulting from direct thermal effects of freezing temperatures on macromolecules, extracellular ice formation, and the generation of reactive oxygen species (ROS). (biomedcentral.com)
  • The availability of Arabidopsis thaliana and rice ( Oryza sativa ) genome sequences has permitted the identification and comparison of the repertoire of serine protease-like proteins in the two plant species. (biomedcentral.com)
  • Despite the differences in genome sizes between Arabidopsis and rice, we identified a very similar number of serine protease-like proteins in the two plant species (206 and 222, respectively). (biomedcentral.com)
  • The systematic analysis of the serine protease-like proteins in the two plant species has provided some insight into the possible functional associations of previously uncharacterised serine protease-like proteins. (biomedcentral.com)
  • Despite this unique composition, plant thylakoid membranes have been shown to assume largely lipid-bilayer dynamic organization. (wikipedia.org)
  • In the plant embryo and in the absence of light, proplastids develop into etioplasts that contain semicrystalline membrane structures called prolamellar bodies. (wikipedia.org)