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Semaphorins
Semaphorins are a class of secreted and membrane proteins that were originally identified as axonal growth cone guidance molecules. They primarily act as short-range inhibitory signals and signal through multimeric receptor complexes. Semaphorins are usually cues to deflect axons from inappropriate regions, especially important in the neural system development. The major class of proteins that act as their receptors are called plexins, with neuropilins as their co-receptors in many cases. The main receptors for semaphorins are plexins, which have established roles in regulating Rho-family GTPases. Recent work shows that plexins can also influence R-Ras, which, in turn, can regulate integrins. Such regulation is probably a common feature of semaphorin signalling and contributes substantially to our understanding of semaphorin biology. Every semaphorin is characterised by the expression of a specific region of about 500 amino acids called the sema domain. Semaphorins were named a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA3A
Semaphorin-3A is a protein that in humans is encoded by the ''SEMA3A'' gene. Function The ''SEMA3A'' gene is a member of the semaphorin family and encodes a protein with an Ig-like C2-type (immunoglobulin-like) domain, a PSI domain and a Sema domain. This secreted Semaphorin-3A protein can function as either a chemorepulsive agent, inhibiting axonal outgrowth, or as a chemoattractive agent, stimulating the growth of apical dendrites. In both cases, the protein is vital for normal neuronal pattern development. Semaphorin-3A is secreted by neurons and surrounding tissue to guide migrating cells and axons in the developing nervous system. Axon pathfinding is the process by which neurons follow very precise paths, sends out axons, and react to specific chemical environments to reach the correct endpoint. The guidance is critical for the precise formation of neurons and the surrounding vasculature. Guidance cues, such as Sema3A, induce the collapse and paralysis of neuronal grow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA4G
Semaphorin-4G is a protein that in humans is encoded by the ''SEMA4G'' gene. Semaphorins are a large family of conserved secreted and membrane associated proteins which possess a semaphoring (Sema) domain and a PSI domain (found in plexins, semaphorins and integrins) in the N-terminal extracellular portion. Based on sequence and structural similarities, semaphorins are put into eight classes: invertebrates contain classes 1 and 2, viruses have class V, and vertebrates contain classes 3-7. Semaphorins serve as axon guidance ligands via multimeric receptor complexes, some (if not all) containing plexin A plexin is a protein which acts as a receptor for semaphorin family signaling proteins. It is classically known for its expression on the surface of axon growth cones and involvement in signal transduction to steer axon growth away from the so ... proteins. This gene encodes a class 4 semaphorin. This gene and the gene for mitochondrial ribosomal protein L43 overlap at map lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA5A
Semaphorin-5A is a protein that in humans is encoded by the ''SEMA5A'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b .... Members of the semaphorin protein family, such as SEMA5A, are involved in axonal guidance during neural development. Semaphorin 5A also plays a role in autism, reducing the ability of neurons to form connections with other neurons in certain brain regions. References Further reading * * * * * * * {{gene-5-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA6C
Semaphorin-6C is a protein that in humans is encoded by the ''SEMA6C'' gene. This gene product is a member of the semaphoring family of proteins. Semaphorins represent important molecular signals controlling multiple aspects of the cellular response that follows CNS injury, and thus may play an important role in neural regeneration Neuroregeneration refers to the regrowth or repair of nervous tissues, cells or cell products. Such mechanisms may include generation of new neurons, glia, axons, myelin, or synapses. Neuroregeneration differs between the peripheral nervous syst .... References Further reading * * * * * * * {{gene-1-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA3B
Semaphorin-3B is a protein that in humans is encoded by the ''SEMA3B'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b .... Function The semaphorin/collapsin family of molecules plays a critical role in the guidance of growth cones during neuronal development. The secreted protein encoded by this gene family member is important in axonal guidance and has been shown to act as a tumor suppressor by inducing apoptosis. References Further reading * * * * * * * * * * {{gene-3-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plexin
A plexin is a protein which acts as a receptor for semaphorin family signaling proteins. It is classically known for its expression on the surface of axon growth cones and involvement in signal transduction to steer axon growth away from the source of semaphorin. Plexin also has implications in development of other body systems by activating GTPase enzymes to induce a number of intracellular biochemical changes leading to a variety of downstream effects. Structure Extracellular All plexins have an extracellular SEMA domain at their N-terminus. This is a structural motif common among all semaphorins and plexins and is responsible for this binding of semaphorin dimers, which are the native conformation for these ligands in vivo. This is followed by alternating plexin, semaphorin, and integrin (PSI) domains and immunoglobulin-like, plexin, and transcription factors (IPT) domains. Each of these is named for the proteins in which their structure is conserved. Collectively, the ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuropilin
Neuropilin is a protein receptor active in neurons. There are two forms of Neuropilins, NRP-1 and NRP-2. Neuropilins are transmembrane glycoproteins, first documented to regulate neurogenesis and angiogenesis by complexing with Plexin receptors/class-3 semaphorin ligands and Vascular Endothelial Growth Factor (VEGF) receptors/VEGF ligands, respectively. Neuropilins predominantly act as co-receptors as they have a very small cytoplasmic domain and thus rely upon other cell surface receptors to transduce their signals across a cell membrane. Recent studies have shown that Neuropilins are multifunctional and can partner with a wide variety of transmembrane receptors. Neuropilins are therefore associated with numerous signalling pathways including those activated by Epidermal Growth Factor (EGF), Fibroblast Growth Factor (FGF), Hepatocyte Growth Factor (HGF), Insulin-like Growth Factor (IGF), Platelet Derived Growth Factor (PDGF) and Transforming Growth Factor beta (TGFβ). Although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plexins
A plexin is a protein which acts as a receptor for semaphorin family signaling proteins. It is classically known for its expression on the surface of axon growth cones and involvement in signal transduction to steer axon growth away from the source of semaphorin. Plexin also has implications in development of other body systems by activating GTPase enzymes to induce a number of intracellular biochemical changes leading to a variety of downstream effects. Structure Extracellular All plexins have an extracellular SEMA domain at their N-terminus. This is a structural motif common among all semaphorins and plexins and is responsible for this binding of semaphorin dimers, which are the native conformation for these ligands in vivo. This is followed by alternating plexin, semaphorin, and integrin (PSI) domains and immunoglobulin-like, plexin, and transcription factors (IPT) domains. Each of these is named for the proteins in which their structure is conserved. Collectively, the ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA7A
Semaphorin 7A, GPI membrane anchor (John Milton Hagen blood group) (SEMA7A) also known as CD108 (Cluster of Differentiation 108), is a human gene. SEMA7A is a membrane-bound semaphorin that associates with cell surfaces via a glycosylphosphatidylinositol (GPI) linkage. SEMA7A is also known as the John-Milton-Hagen (JMH) blood group antigen, an 80-kD glycoprotein expressed on activated lymphocytes and erythrocytes. upplied by OMIMref name="entrez"/> SEMA7A is expressed in various adult tissues such as adipose, colon, esophagus, heart, brain, spleen, testis, lung, ovary, and uterus. Development SEMA7A promotes axonal growth and is involved in mesoderm derived somite formation. Murine embryonic Sema7A expression is highest on day 7, which is indicative of its role on the differentiation of germ layer structure. Embryonic Sema7A expression is noticeable at all developmental stages as well as in the newborn and adult thymus, indicative of a development T-cell role. In wild type neuron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SEMA6A
Semaphorin-6A is a protein that in humans is encoded by the ''SEMA6A'' gene. In melanocytic cells SEMA6A gene expression may be regulated by Microphthalmia-associated transcription factor, MITF. References Further reading * * * * * * * * {{gene-5-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
