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MMP20
Matrix metalloproteinase-20 (MMP-20) also known as enamel metalloproteinase or enamelysin is an enzyme that in humans is encoded by the ''MMP20'' gene. Function Proteins of the matrix metalloproteinase ( MMP) family are involved in the breakdown of extracellular matrix in normal physiological processes, such as embryonic development, reproduction, and tissue remodeling, as well as in disease processes, such as arthritis and metastasis. Most MMP's are secreted as inactive proproteins which are activated when cleaved by extracellular proteinases. MMP-20, also known as enamelysin, appears to be the only MMP that is tooth-specific and it is expressed by cells of different developmental origin (i.e. epithelial ameloblasts and mesenchymal odontoblasts). Clinical significance The human MMP-20 gene contains 10 exons and is part of a cluster of matrix metalloproteinase genes that localize to human chromosome 11q22.3. A mutation in this gene, which alters the normal splice pattern and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amelogenesis Imperfecta
Amelogenesis imperfecta (AI) is a congenital disorder which presents with a rare abnormal formation of the enamel or external layer of the crown of teeth, unrelated to any systemic or generalized conditions. Enamel is composed mostly of mineral, that is formed and regulated by the proteins in it. Amelogenesis imperfecta is due to the malfunction of the proteins in the enamel (ameloblastin, enamelin, tuftelin and amelogenin) as a result of abnormal enamel formation via amelogenesis. People with amelogenesis imperfecta may have teeth with abnormal color: yellow, brown or grey; this disorder can affect any number of teeth of both dentitions. Enamel hypoplasia manifests in a variety of ways depending on the type of AI an individual has (see below), with pitting and plane-form defects common. The teeth have a higher risk for dental cavities and are hypersensitive to temperature changes as well as rapid attrition, excessive calculus deposition, and gingival hyperplasia.American Academy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrix Metalloproteinase
Matrix metalloproteinases (MMPs), also known as matrix metallopeptidases or matrixins, are metalloproteinases that are calcium-dependent zinc-containing endopeptidases; other family members are adamalysins, serralysins, and astacins. The MMPs belong to a larger family of proteases known as the metzincin superfamily. Collectively, these enzymes are capable of degrading all kinds of extracellular matrix proteins, but also can process a number of bioactive molecules. They are known to be involved in the cleavage of cell surface receptors, the release of apoptotic ligands (such as the FAS ligand), and chemokine/cytokine inactivation. MMPs are also thought to play a major role in cell behaviors such as cell proliferation, migration (adhesion/dispersion), differentiation, angiogenesis, apoptosis, and host defense. They were first described in vertebrates (1962), including humans, but have since been found in invertebrates and plants. They are distinguished from other endopeptida ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrix Metalloproteinases
Matrix metalloproteinases (MMPs), also known as matrix metallopeptidases or matrixins, are metalloproteinases that are calcium-dependent zinc-containing endopeptidases; other family members are adamalysins, serralysins, and astacins. The MMPs belong to a larger family of proteases known as the metzincin superfamily. Collectively, these enzymes are capable of degrading all kinds of extracellular matrix proteins, but also can process a number of Biological activity, bioactive molecules. They are known to be involved in the cleavage of cell surface Receptor (biochemistry), receptors, the release of apoptosis, apoptotic ligands (such as the FAS ligand), and chemokine/cytokine inactivation. MMPs are also thought to play a major role in cell behaviors such as cell proliferation, cell migration, migration (cell adhesion, adhesion/dispersion), Cellular differentiation, differentiation, angiogenesis, apoptosis, and Immune system, host defense. They were first described in vertebrates (19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extracellular Matrix
In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and biochemical support to surrounding cells. Because multicellularity evolved independently in different multicellular lineages, the composition of ECM varies between multicellular structures; however, cell adhesion, cell-to-cell communication and differentiation are common functions of the ECM. The animal extracellular matrix includes the interstitial matrix and the basement membrane. Interstitial matrix is present between various animal cells (i.e., in the intercellular spaces). Gels of polysaccharides and fibrous proteins fill the Interstitial fluid, interstitial space and act as a compression buffer against the stress placed on the ECM. Basement membranes are sheet-like depositions of ECM on which various epithelial cells rest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteinase
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in many biological functions, including digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life and viruses. They have independently evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms. Hierarchy of proteases Based on catalytic residue Proteases can be classified into seven broad groups: * Serine proteases - ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ameloblast
Ameloblasts are cells present only during tooth development that deposit tooth enamel, which is the hard outermost layer of the tooth forming the surface of the crown. Structure Each ameloblast is a columnar cell approximately 4 micrometers in diameter, 40 micrometers in length and is hexagonal in cross section. The secretory end of the ameloblast ends in a six-sided pyramid-like projection known as the Tomes' process. The angulation of the Tomes' process is significant in the orientation of enamel rods, the basic unit of tooth enamel. Distal terminal bars are junctional complexes that separate the Tomes' processes from ameloblast proper. Development Ameloblasts are derived from oral epithelium tissue of ectodermal origin. Their differentiation from preameloblasts (whose origin is from inner enamel epithelium) is a result of signaling from the ectomesenchymal cells of the dental papilla. Initially the preameloblasts will differentiate into presecretory ameloblasts and then into s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odontoblast
In vertebrates, an odontoblast is a cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the formation of dentin, the substance beneath the tooth enamel on the crown and the cementum on the root. Structure Odontoblasts are large columnar cells, whose cell bodies are arranged along the interface between dentin and pulp, from the crown to cervix to the root apex in a mature tooth. The cell is rich in endoplasmic reticulum and Golgi complex, especially during primary dentin formation, which allows it to have a high secretory capacity; it first forms the collagenous matrix to form predentin, then mineral levels to form the mature dentin. Odontoblasts form approximately 4 μm of predentin daily during tooth development.Ten Cate's Oral Histology, Nanci, Elsevier, 2013, page 170 During secretion after differentiation from the outer cells of the dental papilla, it is noted that it is polarized so its nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MEROPS
MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibitors by Rawlings ''et al.'' in 2004.Rawlings, N.D., Tolle, D.P. & Barrett, A.J. (2004) "Evolutionary families of peptidase inhibitors." ''Biochem J'' 378, 705-716. The most recent version, MEROPS 12.3, was released in September 2020. Overview The classification is based on similarities at the tertiary and primary structural levels. Comparisons are restricted to that part of the sequence directly involved in the reaction, which in the case of a peptidase must include the active site, and for a protein inhibitor the reactive site. The classification is hierarchical: sequences are assembled into families, and families are assembled into clans. Each peptidase, family, and clan has a unique identifier. Classification Family The families of pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
