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Membrane Ruffling
Within molecular and cell biology Membrane ruffling (also known as cell ruffling) is the formation of a motile cell surface that contains a meshwork of newly polymerized actin filaments. It can also be regarded as one of the earliest structural changes observed in the cell. The GTP-binding protein Rac is the regulator of this membrane ruffling. Changes in the Polyphosphoinositide metabolism and changes in Ca2+ level of the cell may also play an important role. A number of actin-binding and organizing proteins localize to membrane ruffles and potentially target to transducing molecules. Characteristic feature of migrating cells Membrane ruffling is a characteristic feature of many actively migrating cells. When the membrane is unable to attach to the substrate, the membrane protrusion is recycled back into the cell. The ruffling of membranes is thought to be controlled by a group of enzymes known as Rho GTPases, specifically RhoA, Rac1 and cdc42. Bacterial infection Some bacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Biology
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actin Filaments
Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other proteins in the cell. Microfilaments are usually about 7 nm in diameter and made up of two strands of actin. Microfilament functions include cytokinesis, amoeboid movement, cell motility, changes in cell shape, endocytosis and exocytosis, cell contractility, and mechanical stability. Microfilaments are flexible and relatively strong, resisting buckling by multi-piconewton compressive forces and filament fracture by nanonewton tensile forces. In inducing cell motility, one end of the actin filament elongates while the other end contracts, presumably by myosin II molecular motors. Additionally, they function as part of actomyosin-driven contractile molecular motors, wherein the thin filaments serve as tensile platforms for myosin's ATP-dep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rac (GTPase)
Rac is a subfamily of the Rho family of GTPases, small (~21 kDa) signaling G proteins (more specifically a GTPase). Just as other G proteins, Rac acts as a molecular switch, remaining inactive while bound to GDP and activated once GEFs remove GDP, permitting GTP to bind. When bound to GTP, Rac is activated. In its activated state, Rac participates in the regulation of cell movement, through its involvement in structural changes to the actin Cytoskeleton. By changing the cytoskeletal dynamics within the cell, Rac-GTPases are able to facilitate the recruitment of neutrophils to the infected tissues, and to regulate degranulation of azurophil and integrin-dependent phagocytosis. Activated Rac also regulates the effector functions of the target proteins involved in downstream signaling. As an essential subunit of NOX2 (NADPH oxidase enzyme complex), Rac is required for ROS (reactive oxygen species) production involved in the formation of NETs (neutrophil extracellular traps, thus, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rho Family Of GTPases
The Rho family of GTPases is a family of small (~21 kDa) signaling G proteins, and is a subfamily of the Ras superfamily. The members of the Rho GTPase family have been shown to regulate many aspects of intracellular actin dynamics, and are found in all eukaryotic kingdoms, including yeasts and some plants. Three members of the family have been studied in detail: Cdc42, Rac1, and RhoA. All G proteins are "molecular switches", and Rho proteins play a role in organelle development, cytoskeletal dynamics, cell movement, and other common cellular functions. History Identification of the Rho family of GTPases began in the mid-1980s. The first identified Rho member was RhoA, isolated serendipitously in 1985 from a low stringency cDNA screening. Rac1 and Rac2 were identified next, in 1989 followed by Cdc42 in 1990. Eight additional mammalian Rho members were identified from biological screenings until the late 1990s, a turning point in biology where availability of complete genome seq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RhoA
Transforming protein RhoA, also known as Ras homolog family member A (RhoA), is a small GTPase protein in the Rho family of GTPases that in humans is encoded by the ''RHOA'' gene. While the effects of RhoA activity are not all well known, it is primarily associated with cytoskeleton regulation, mostly actin stress fibers formation and actomyosin contractility. It acts upon several effectors. Among them, ROCK1 (Rho-associated, coiled-coil containing protein kinase 1) and DIAPH1 (Diaphanous Homologue 1, a.k.a. hDia1, homologue to mDia1 in mouse, diaphanous in ''Drosophila'') are the best described. RhoA, and the other Rho GTPases, are part of a larger family of related proteins known as the Ras superfamily, a family of proteins involved in the regulation and timing of cell division. RhoA is one of the oldest Rho GTPases, with homologues present in the genomes since 1.5 billion years. As a consequence, RhoA is somehow involved in many cellular processes which emerged throughout evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enteropathogenic Escherichia Coli
''Escherichia coli'' ( Anglicized to ; commonly abbreviated ''E. coli'') is a gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most ''E. coli'' strains are harmless, but pathogenic varieties cause serious food poisoning, septic shock, meningitis, or urinary tract infections in humans. Unlike normal flora ''E. coli'', the pathogenic varieties produce toxins and other virulence factors that enable them to reside in parts of the body normally not inhabited by ''E. coli'', and to damage host cells. These pathogenic traits are encoded by virulence genes carried only by the pathogens. Introduction ''E. coli'' and related bacteria constitute about 0.1% of gut flora, and fecal–oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for only a limited amount of time, which makes them ideal indicator organisms to test envir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterohemorrhagic Escherichia Coli
Shigatoxigenic ''Escherichia coli'' (STEC) and verotoxigenic ''E. coli'' (VTEC) are strains of the bacterium ''Escherichia coli'' that produce Shiga toxin (or verotoxin). Only a minority of the strains cause illness in humans. The ones that do are collectively known as enterohemorrhagic ''E. coli'' (EHEC) and are major causes of foodborne illness. When infecting the large intestine of humans, they often cause gastroenteritis, enterocolitis, and bloody diarrhea (hence the name "enterohemorrhagic") and sometimes cause a severe complication called hemolytic-uremic syndrome (HUS). Cattle is an important natural reservoir for EHEC because the colonised adult ruminants are asymptomatic. This is because they lack vascular expression of the target receptor for Shiga toxins. The group and its subgroups are known by various names. They are distinguished from other strains of intestinal pathogenic ''E. coli'' including enterotoxigenic ''E. coli'' (ETEC), enteropathogenic ''E. coli' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Three Secretion System
Type three secretion system (often written Type III secretion system and abbreviated TTSS or T3SS, also called Injectisome) is a protein appendage found in several Gram-negative bacteria. In pathogenic bacteria, the needle-like structure is used as a sensory probe to detect the presence of eukaryotic organisms and secrete proteins that help the bacteria infect them. The secreted effector proteins are secreted directly from the bacterial cell into the eukaryotic (host) cell, where they exert a number of effects that help the pathogen to survive and to escape an immune response. Overview The term Type III secretion system was coined in 1993. This secretion system is distinguished from at least five other secretion systems found in Gram-negative bacteria. Many animal and plant associated bacteria possess similar T3SSs. These T3SSs are similar as a result of divergent evolution and phylogenetic analysis supports a model in which gram-negative bacteria can transfer the T3SS gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components, microfilaments, intermediate filaments and microtubules, and these are all capable of rapid growth or disassembly dependent on the cell's requirements. A multitude of functions can be performed by the cytoskeleton. Its primary function is to give the cell its shape and mechanical resistance to deformation, and through association with extracellular connective tissue and other cells it stabilizes entire tissues. The cytoskeleton can also contract, thereby deforming the cell and the cell's environment and allowing cells to migrate. Moreover, it is involved in many cell signaling pathways and in the uptake of extracellular material ( endocytosis), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
