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Actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm. An actin protein is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous), both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division. Actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle mov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfilaments
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfilament
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTG1
Actin, cytoplasmic 2, or gamma-actin is a protein that in humans is encoded by the ''ACTG1'' gene. Gamma-actin is widely expressed in cellular cytoskeletons of many tissues; in adult striated muscle cells, gamma-actin is localized to Z-discs and costamere structures, which are responsible for force transduction and transmission in muscle cells. Mutations in ''ACTG1'' have been associated with nonsyndromic hearing loss and Baraitser-Winter syndrome, as well as susceptibility of adolescent patients to vincristine toxicity. Structure Human gamma-actin is 41.8 kDa in molecular weight and 375 amino acids in length. Actins are highly conserved proteins that are involved in various types of cell motility, and maintenance of the cytoskeleton. In vertebrates, three main groups of actin paralogs, alpha, beta, and gamma, have been identified. The alpha actins are found in muscle tissues and are a major constituent of the sarcomere contractile apparatus. The beta and gamma actins co- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTA1
Actin, alpha skeletal muscle is a protein that in humans is encoded by the ''ACTA1'' gene. Actin alpha 1 which is expressed in skeletal muscle is one of six different actin isoforms which have been identified. Actins are highly conserved proteins that are involved in cell motility, structure and integrity. Alpha actins are a major constituent of the contractile apparatus. Skeletal actin gene expression Skeletal alpha actin expression is induced by stimuli and conditions known to cause muscle formation. Such conditions result in fusion of committed cells (satellite cells) into myotubes, to form muscle fibers. Skeletal actin itself, when expressed, causes expression of several other "myogenic genes", which are essential to muscle formation. One key transcription factor that activates skeletal actin gene expression is Serum Response Factor ("SRF"), a protein that binds to specific sites on the promoter DNA of the actin gene. SRF may bring a number of other proteins to the promoter of ... [...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 and or disassembly depending on the cell's requirements. Cytoskeleton can perform many functions. 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 segregation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscle Contraction
Muscle contraction is the activation of Tension (physics), tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state. For the contractions to happen, the muscle cells must rely on the change in action of two types of Myofilament, filaments: thin and thick filaments. The major constituent of thin filaments is a chain formed by helical coiling of two strands of actin, and thick filaments dominantly consist of chains of the Motor protein, motor-protein myosin. Together, these two filaments form myofibrils - the basic functional organelles in the skeletal muscle system. In vertebrates, Muscle cell#Muscle contraction in striated muscle, skele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myofibril
A myofibril (also known as a muscle fibril or sarcostyle) is a basic rod-like organelle of a muscle cell. Skeletal muscles are composed of long, tubular cells known as Skeletal muscle#Skeletal muscle cells, muscle fibers, and these cells contain many chains of myofibrils. Each myofibril has a diameter of 1–2 micrometres. They are created during embryogenesis, embryonic development in a process known as myogenesis. Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together. These proteins are organized into Thick filaments, thick, thin filaments, thin, and elastic filament, elastic myofilaments, which repeat along the length of the myofibril in sections or units of contraction called sarcomeres. Muscle contraction, Muscles contract by sliding filament theory, sliding the thick myosin, and thin actin myofilaments along each other. Structure Each myofibril has a diameter of between 1 and 2 micrometres (μm). The filamen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokinesis
Cytokinesis () is the part of the cell division process and part of mitosis during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis. During cytokinesis the spindle apparatus partitions and transports duplicated chromatids into the cytoplasm of the separating daughter cells. It thereby ensures that chromosome number and complement are maintained from one generation to the next and that, except in special cases, the daughter cells will be functional copies of the parent cell. After the completion of the telophase and cytokinesis, each daughter cell enters the interphase of the cell cycle. Particular functions demand various deviations from the process of symmetrical cytokinesis; for example in oogenesis in animals the ovum takes almost all the cytoplasm and organelles. This leaves very little for the resulting polar bodies, which in most spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTB
Actin beta (HUGO Gene Nomenclature Committee abbreviation ''ACTB''/ACTB) is one of six different actin isoforms which have been identified in humans. This is one of the two nonmuscle cytoskeletal actins. Actins are highly conserved proteins that are involved in cell motility, structure and integrity. Alpha actins are a major constituent of the contractile apparatus. Interactions Actin beta has been shown to interact with SPTBN2. In addition, RNA-binding protein Sam68 was found to interact with the mRNA encoding actin beta, which regulates the synaptic formation of the dendritic spines with its cytoskeletal components. Actin beta has been shown to activate eNOS, thereby increasing NO production. An eight-amino acid motif (326-333) in eNOS has been shown to mediate the interaction between actin and eNOS. Clinical relevance Recurrent mutations in this gene have been associated to cases of diffuse large B-cell lymphoma. De novo gain-of-function mutations in this gene i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Junction
Cell junctions or junctional complexes are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring Cell (biology), cells or between a cell and the extracellular matrix in animals. They also maintain the paracellular barrier of epithelia and control paracellular transport. Cell junctions are especially abundant in epithelial tissues. Combined with cell adhesion molecules and extracellular matrix, cell junctions help hold animal cells together. Cell junctions are also especially important in enabling communication between neighboring cells via specialized protein complexes called gap junction, communicating (gap) junctions. Cell junctions are also important in reducing stress placed upon cells. In plants, similar communication channels are known as plasmodesmata, and in fungus, fungi they are called septal pores. Types In vertebrates, there are three major types of cell junction: *Adherens junctions, desmosomes and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of Outline of life forms, life forms alongside the two groups of prokaryotes: the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms, but given their generally much larger size, their collective global biomass is much larger than that of prokaryotes. The eukaryotes emerged within the archaeal Kingdom (biology), kingdom Asgard (Archaea), Promethearchaeati and its sole phylum Promethearchaeota. This implies that there are only Two-domain system, two domains of life, Bacteria and Archaea, with eukaryotes incorporated among the Archaea. Eukaryotes first emerged during the Paleoproterozoic, likely as Flagellated cell, flagellated cells. The leading evolutiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
