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Actinin
Actinin is a microfilament protein. Alpha-actinin-1 is necessary for the attachment of actin myofilaments to the Z-lines in skeletal muscle cells, and to the dense bodies in smooth muscle cells. The functional protein is an anti-parallel dimer, which cross-links the thin filaments in adjacent sarcomeres, and therefore coordinates contractions between sarcomeres in the horizontal axis. The non-sarcomeric alpha-actinins, encoded by ''ACTN1'' and ''ACTN4'', are widely expressed. ''ACTN2'' expression is found in both cardiac and skeletal muscle, whereas ''ACTN3'' is limited to the latter. Both ends of the rod-shaped alpha-actinin dimer contain actin-binding domains. Mutations in ''ACTN4'' can cause the kidney disease focal segmental glomerulosclerosis (FSGS). See also * Actin * Muscle contraction Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle ten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTN2
Alpha-actinin-2 is a protein which in humans is encoded by the ''ACTN2'' gene. This gene encodes an alpha-actinin isoform that is expressed in both skeletal and cardiac muscles and functions to anchor myofibrillar actin thin filaments and titin to Z-discs. Structure Alpha-actinin-2 is a 103.8 kDa protein composed of 894 amino acids. Each molecule is rod-shaped (35 nm in length) and it homodimerizes in an anti-parallel fashion. Each monomer has an N-terminal actin-binding region composed of two calponin homology domains, two C-terminal EF hand domains, and four tandem spectrin-like repeats form the rod domain in the central region of the molecule. The high-resolution crystal structure of human alpha-actinin 2 at 3.5 Å was recently resolved. Alpha actinins belong to the spectrin gene superfamily which represents a diverse group of actin-binding cytoskeletal proteins, including spectrin, dystrophin, utrophin and fimbrin. Skeletal, cardiac, and smooth muscle isoforms are local ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTN3
Alpha-actinin-3, also known as alpha-actinin skeletal muscle isoform 3 or F-actin cross-linking protein, is a protein that in humans is encoded by the ''ACTN3'' gene (named sprinter gene, speed gene or athlete gene) located on chromosome 11. All people have two copies (alleles) of this gene. Alpha-actinin is an actin-binding protein with multiple roles in different cell types. This gene expression is limited to skeletal muscle. It is localized to the Z-disc and analogous dense bodies, where it helps to anchor the myofibrillar actin filaments. Fast versus slow twitch muscle fibers Skeletal muscle is composed of long cylindrical cells called muscle fibers. There are two types of muscle fibers, slow twitch or muscle contraction (type I) and fast twitch (type II). Slow twitch fibers are more efficient in using oxygen to generate energy, while fast twitch fibers are less efficient. However, fast twitch fibers fire more rapidly, allowing them to generate more power than slow twitch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTN1
Alpha-actinin-1 is a protein that in humans is encoded by the ''ACTN1'' gene. Function Alpha actinins belong to the spectrin gene superfamily which represents a diverse group of cytoskeletal proteins, including the alpha and beta spectrins and dystrophins. Alpha-actinin-1 is an F-actin cross-linking protein – a bundling protein that is thought to anchor actin to a number of intracellular structures. Alpha-actinin-1 is a non-muscle cytoskeletal isoform found along microfilament bundles and adherens-type junctions, where it is involved in binding actin to the membrane. In contrast, skeletal, cardiac, and smooth muscle isoforms are localized to the Z-disc and analogous dense bodies, where they help anchor the myofibrillar actin filaments. Interactions Alpha-actinin-1 has been shown to interact with: * CDK5R1, * CDK5R2, * Collagen, type XVII, alpha 1, * GIPC1, * PDLIM1, * Protein kinase N1, * SSX2IP, and * Zyxin. *PTPRT (PTPrho) See also * Actinin Actinin is a microfilame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-actinin-1
Alpha-actinin-1 is a protein that in humans is encoded by the ''ACTN1'' gene. Function Alpha actinins belong to the spectrin gene superfamily which represents a diverse group of cytoskeletal proteins, including the alpha and beta spectrins and dystrophins. Alpha-actinin-1 is an F-actin cross-linking protein – a bundling protein that is thought to anchor actin to a number of intracellular structures. Alpha-actinin-1 is a non-muscle cytoskeletal isoform found along microfilament bundles and adherens-type junctions, where it is involved in binding actin to the membrane. In contrast, skeletal, cardiac, and smooth muscle isoforms are localized to the Z-disc and analogous dense bodies, where they help anchor the myofibrillar actin filaments. Interactions Alpha-actinin-1 has been shown to interact with: * CDK5R1, * CDK5R2, * Collagen, type XVII, alpha 1, * GIPC1, * PDLIM1, * Protein kinase N1, * SSX2IP, and * Zyxin. *PTPRT (PTPrho) See also * Actinin Actinin is a microfilamen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACTN4
Alpha-actinin-4 is a protein that in humans is encoded by the ''ACTN4'' gene. Alpha actinins belong to the spectrin gene superfamily which represents a diverse group of cytoskeletal proteins, including the alpha and beta spectrins and dystrophins. Alpha actinin is an actin-binding protein with multiple roles in different cell types. In nonmuscle cells, the cytoskeletal isoform is found along microfilament bundles and adherens-type junctions, where it is involved in binding actin to the membrane. In contrast, skeletal, cardiac, and smooth muscle isoforms are localized to the Z-disc and analogous dense bodies, where they help anchor the myofibrillar actin filaments. This gene encodes a nonmuscle, alpha actinin isoform which is concentrated in the cytoplasm, and thought to be involved in metastatic processes. Mutations in this gene have been associated with focal and segmental glomerulosclerosis. Interactions Alpha-actinin-4 has been shown to interact with PDLIM1, Sodium-hydrog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 movement, cell sign ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 movement, cell sign ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smooth Muscle Tissue
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit muscle, the whole bundle or sheet of smooth muscle cells contracts as a syncytium. Smooth muscle is found in the walls of hollow organs, including the stomach, intestines, bladder and uterus; in the walls of passageways, such as blood, and lymph vessels, and in the tracts of the respiratory, urinary, and reproductive systems. In the eyes, the ciliary muscles, a type of smooth muscle, dilate and contract the iris and alter the shape of the lens. In the skin, smooth muscle cells such as those of the arrector pili cause hair to stand erect in response to cold temperature or fear. Structure Gross anatomy Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smooth Muscle Cells
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit muscle, the whole bundle or sheet of smooth muscle cells contracts as a syncytium. Smooth muscle is found in the walls of hollow organs, including the stomach, intestines, bladder and uterus; in the walls of passageways, such as blood, and lymph vessels, and in the tracts of the respiratory, urinary, and reproductive systems. In the eyes, the ciliary muscles, a type of smooth muscle, dilate and contract the iris and alter the shape of the lens. In the skin, smooth muscle cells such as those of the arrector pili cause hair to stand erect in response to cold temperature or fear. Structure Gross anatomy Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. M ... [...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 ATP-de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcomeres
A sarcomere (Greek σάρξ ''sarx'' "flesh", μέρος ''meros'' "part") is the smallest functional unit of striated muscle tissue. It is the repeating unit between two Z-lines. Skeletal muscles are composed of tubular muscle cells (called muscle fibers or myofibers) which are formed during embryonic myogenesis. Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes. The costamere is a different component that connects the sarcomere to the sarcolemma. Two of the important proteins are myosin, which forms the thick filament, and actin, which forms the thin filament. Myosin has a long, fibrous tail and a globular head, which binds to actin. The myosin head also binds to ATP, which is the source of energy for muscle movement. Myosi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcomere
A sarcomere (Greek σάρξ ''sarx'' "flesh", μέρος ''meros'' "part") is the smallest functional unit of striated muscle tissue. It is the repeating unit between two Z-lines. Skeletal muscles are composed of tubular muscle cells (called muscle fibers or myofibers) which are formed during embryonic myogenesis. Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes. The costamere is a different component that connects the sarcomere to the sarcolemma. Two of the important proteins are myosin, which forms the thick filament, and actin, which forms the thin filament. Myosin has a long, fibrous tail and a globular head, which binds to actin. The myosin head also binds to ATP, which is the source of energy for muscle movement. Myos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
