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Dystrophin
Dystrophin is a rod-shaped cytoplasmic protein, and a vital part of a protein complex that connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix through the cell membrane. This complex is variously known as the costamere or the dystrophin-associated protein complex (DAPC). Many muscle proteins, such as α-dystrobrevin, syncoilin, synemin, sarcoglycan, dystroglycan, and sarcospan, colocalize with dystrophin at the costamere. It has a molecular weight of 427 kDa Dystrophin is coded for by the ''DMD'' gene – the largest known human gene, covering 2.4 megabases (0.08% of the human genome) at locus Xp21. The primary transcript in muscle measures about 2,100 kilobases and takes 16 hours to transcribe; the mature mRNA measures 14.0 kilobases. The 79-exon muscle transcript codes for a protein of 3685 amino acid residues. Spontaneous or inherited mutations in the dystrophin gene can cause different forms of muscular dystrophy, a disease characterized by p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystrobrevin
Dystrobrevin is a protein that binds to dystrophin in the costamere of skeletal muscle cells. In humans, there are at least two isoforms of dystrobrevin, dystrobrevin alpha and dystrobrevin beta. Dystrobrevins are members of dystrophin-related protein family which are thought to play an important role in intracellular signal transduction and provide a membrane scaffold in muscle. Defects in dystrobrevins and their associated proteins cause a range of neuromuscular diseases such as muscular dystrophies. Dystrobrevin was first identified by isolating from the electric organ of the electric ray '' Torpedo californica.'' It is a phosphoprotein, which weights 87 kDa, associated with the postsynaptic membrane at the cytoplasmic face. Dystrobrevin proteins have been said to participates in the formation and stability of synapses because it copurifies with acetylcholine receptors from ''Torpedo'' electric organ membranes. In 1997, an experiment was done using the yeast two-hybrid m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy that primarily affects boys. Muscle weakness usually begins around the age of four, and worsens quickly. Muscle loss typically occurs first in the thighs and pelvis followed by the arms. This can result in trouble standing up. Most are unable to walk by the age of 12. Affected muscles may look larger due to increased fat content. Scoliosis is also common. Some may have intellectual disability. Females with a single copy of the defective gene may show mild symptoms. The disorder is X-linked recessive. About two thirds of cases are inherited from a person's mother, while one third of cases are due to a new mutation. It is caused by a mutation in the gene for the protein dystrophin. Dystrophin is important to maintain the muscle fiber's cell membrane. Genetic testing can often make the diagnosis at birth. Those affected also have a high level of creatine kinase in their blood. Although there is no know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystrophin-associated Protein Complex
The dystrophin-associated protein complex, also known as the dystrophin-associated glycoprotein complex is a multiprotein complex that includes dystrophin and the dystrophin-associated proteins. It is one of the two protein complexes that make up the costamere in striated muscle cells. The other complex is the ''integrin-vinculin-talin complex''. Structure The dystrophin-associated protein complex includes dystrophin. Dystrophin binds to actin of the cytoskeleton, and also to proteins in the extracellular matrix. The dystrophin-associated protein complex also contains dystrophin-associated proteins. This includes a four subunit sarcoglycan complex, which is fixed to dystrophin in muscle cells. In the epithelia of the kidney, dystrophin may be replaced with utrophin. Aquaporin 4 may be connected to the dystrophin-associated protein complex. Function The dystrophin-associated protein complex is important for cell structure and cell signalling. It is one of two protein comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystroglycan
Dystroglycan is a protein that in humans is encoded by the ''DAG1'' gene. Dystroglycan is one of the dystrophin-associated glycoproteins, which is encoded by a 5.5 kb transcript in ''Homo sapiens'' on chromosome 3. There are two exons that are separated by a large intron. The spliced exons code for a protein product that is finally cleaved into two non-covalently associated subunits, lpha(N-terminal) and eta(C-terminal). Function In skeletal muscle the dystroglycan complex works as a transmembrane linkage between the extracellular matrix and the cytoskeleton. lphadystroglycan is extracellular and binds to merosin lpha2 laminin in the basement membrane, while etadystroglycan is a transmembrane protein and binds to dystrophin, which is a large rod-like cytoskeletal protein, absent in Duchenne muscular dystrophy patients. Dystrophin binds to intracellular actin cables. In this way, the dystroglycan complex, which links the extracellular matrix to the intracellular actin cab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystroglycan
Dystroglycan is a protein that in humans is encoded by the ''DAG1'' gene. Dystroglycan is one of the dystrophin-associated glycoproteins, which is encoded by a 5.5 kb transcript in ''Homo sapiens'' on chromosome 3. There are two exons that are separated by a large intron. The spliced exons code for a protein product that is finally cleaved into two non-covalently associated subunits, lpha(N-terminal) and eta(C-terminal). Function In skeletal muscle the dystroglycan complex works as a transmembrane linkage between the extracellular matrix and the cytoskeleton. lphadystroglycan is extracellular and binds to merosin lpha2 laminin in the basement membrane, while etadystroglycan is a transmembrane protein and binds to dystrophin, which is a large rod-like cytoskeletal protein, absent in Duchenne muscular dystrophy patients. Dystrophin binds to intracellular actin cables. In this way, the dystroglycan complex, which links the extracellular matrix to the intracellular actin cab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Costamere
The costamere is a structural-functional component of striated muscle cells which connects the sarcomere of the muscle to the cell membrane (i.e. the sarcolemma).20: 2327-2331 Costameres are sub-sarcolemmal protein assemblies circumferentially aligned in register with the Z-disk of peripheral myofibrils. They physically couple force-generating sarcomeres with the sarcolemma in striated muscle cells and are thus considered one of several " Achilles' heels" of skeletal muscle, a critical component of striated muscle morphology which, when compromised, is thought to directly contribute to the development of several distinct myopathies. The dystrophin-associated protein complex, also referred to as the dystrophin-associated glycoprotein complex (DGC or DAGC), contains various integral and peripheral membrane proteins such as dystroglycans and sarcoglycans, which are thought to be responsible for linking the internal cytoskeletal system of individual myofibers to structural proteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcospan
Originally identified as Kirsten ras associated gene (krag), Sarcospan (SSPN) is a 25-kDa transmembrane protein located in the dystrophin-associated protein complex of skeletal muscle cells, where it is most abundant. It contains four transmembrane spanning helices with both N- and C-terminal domains located intracellularly. Loss of SSPN expression occurs in patients with Duchenne muscular dystrophy. Dystrophin Dystrophin is a rod-shaped cytoplasmic protein, and a vital part of a protein complex that connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix through the cell membrane. This complex is variously known as the costa ... is required for proper localization of SSPN. SSPN is also an essential regulator of Akt signaling pathways. Without SSPN, Akt signaling pathways will be hindered and muscle regeneration will not occur. Sarcospan in Muscular Dystrophy The loss of dystrophin results in muscular dystrophy. SSPN upregulates the levels of Utro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscular Dystrophy
Muscular dystrophies (MD) are a genetically and clinically heterogeneous group of rare neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscles over time. The disorders differ as to which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin. Some types are also associated with problems in other organs. Over 30 different disorders are classified as muscular dystrophies. Of those, Duchenne muscular dystrophy (DMD) accounts for approximately 50% of cases and affects males beginning around the age of four. Other relatively common muscular dystrophies include Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy, whereas limb–girdle muscular dystrophy and congenital muscular dystrophy are themselves groups of several – usually ultrarare – genetic disorders. Muscular dystrophies are caused by mutations in genes, usually those involved in making muscle proteins. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syncoilin
Discovery Syncoilin is a muscle-specific atypical type III intermediate filament protein encoded in the human by the gene ''SYNC''. It was first isolated as a binding partner to α-dystrobrevin, as determined by a yeast two-hybrid assay. Later, a yeast two-hybrid method was used to demonstrate that syncoilin is a binding partner of desmin. These binding partners suggest that syncoilin acts as a mechanical "linker" between the sarcomere Z-disk (where desmin is localized) and the dystrophin-associated protein complex (where α-dystrobrevin is localized). However, the specific ''in vivo'' functions of syncoilin have not yet been determined. Through the use of Western blotting techniques, a second species of syncoilin was found. This species was 55kDa in size, whereas the original species of syncoilin was 64kDa in size. This discovery inspired scientists to use gene splicing to identify two new isoforms called SYNC2 and SYNC3. Abnormally high levels of syncoilin have been shown ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myofilament
Myofilaments are the three protein filaments of myofibrils in muscle cells. The main proteins involved are myosin, actin, and titin. Myosin and actin are the ''contractile proteins'' and titin is an elastic protein. The myofilaments act together in muscle contraction, and in order of size are a thick one of mostly myosin, a thin one of mostly actin, and a very thin one of mostly titin. Types of muscle tissue are striated skeletal muscle and cardiac muscle, obliquely striated muscle (found in some invertebrates), and non-striated smooth muscle. Various arrangements of myofilaments create different muscles. Striated muscle has transverse bands of filaments. In obliquely striated muscle, the filaments are staggered. Smooth muscle has irregular arrangements of filaments. Structure There are three different types of myofilaments: thick, thin, and elastic filaments. *Thick filaments consist primarily of a type of myosin, a motor protein – myosin II. Each thick filament is approx ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcoglycan
The sarcoglycans are a family of transmembrane proteins (α, β, γ, δ or ε) involved in the protein complex responsible for connecting the muscle fibre cytoskeleton to the extracellular matrix, preventing damage to the muscle fibre sarcolemma through shearing forces. The dystrophin glycoprotein complex (DGC) is a membrane-spanning complex that links the interior cytoskeleton to the extracellular matrix in muscle. The sarcoglycan complex is a subcomplex within the DGC and is composed of six muscle-specific, transmembrane proteins (alpha-, beta-, gamma-, delta-, epsilon-,and zeta-sarcoglycan). The sarcoglycans are asparagine-linked glycosylated proteins with single transmembrane domains. The disorders caused by the mutations of the sarcoglycans are called sarcoglycanopathies. Mutations in the α, β, γ or δ genes (not ε) encoding these proteins can lead to the associated limb-girdle muscular dystrophy. Genes * SGCA * SGCB * SGCD * SGCE * SGCG Gamma-sarcoglycan is a prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synemin
Synemin, also known as desmuslin, is a protein that in humans is encoded by the ''SYNM'' gene. Synemin is an intermediate filament (IF) family member. IF proteins are cytoskeletal proteins that confer resistance to mechanical stress and are encoded by a dispersed multigene family. This protein has been found to form a linkage between desmin, which is a subunit of the IF network, and the extracellular matrix, and provides an important structural support in muscle. Function Synemin is an intermediate filament (IF) and, like other IFs, primarily functions to integrate mechanical stress and maintain structural integrity in eukaryotic cells. While it has been observed in a variety of cell types, it has been best studied in the sarcomere of skeletal myocytes. It localizes at the Z-disk and has been shown to bind to α-dystrobrevin, α-actinin, and desmin to act as a mechanical linker in transmitting force laterally throughout the tissue, especially between the contractile myofibrils a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
