| AMBN | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | AMBN , AI1F, Sheathlin, ameloblastin | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 601259 MGI: 104655 HomoloGene: 7625 GeneCards: AMBN | ||||||||||||||||||||||||||||||||||||||||||||||||||
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| Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Ameloblastin (abbreviated AMBN and also known as sheathlin or amelin) is an enamel matrix protein that in humans is encoded by the AMBN gene. [5]
Ameloblastin is a specific protein found in tooth enamel. Although less than 5% of enamel consists of protein, ameloblastins constitute 5–10% of all enamel protein, making it the second most abundant enamel matrix protein. [6] This protein is formed by ameloblasts during the early secretory to late maturation stages of amelogenesis. Although not completely understood, the function of ameloblastins is believed to be in controlling the elongation of enamel crystals and generally directing enamel mineralization during tooth development. Ameloblastin helps in the growth of a crystalline enameloid layer consisting of randomly oriented short enamel crystals. [7] Ameloblastin cleavage products are found in the sheath space between rod and interrod enamel, while intact ameloblastin accumulates on the enamel rods. This difference in localization is thought to maintain the boundary between rod and interrod enamel. [6] [8]
Ameloblastin is generally implicated in enamel development, but may also have a role in root development. [6] Other possible actions include bone remodeling and repair, although this function has yet to be definitively proven. [6]
Other significant proteins in enamel are amelogenins, enamelins, and tuftelins.
Mutations in AMBN cause amelogenesis imperfecta, a disease characterized by abnormal enamel formation resulting in discolored, pitted, or spotted enamel. [9] These mutations are rare, and follow an autosomal recessive pattern of inheritance. [6]
Tooth enamel is one of the four major tissues that make up the tooth in humans and many animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are dentin, cementum, and dental pulp. It is a very hard, white to off-white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink. In rare circumstances enamel fails to form, leaving the underlying dentin exposed on the surface.
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.
Amelogenins are a group of protein isoforms produced by alternative splicing or proteolysis from the AMELX gene, on the X chromosome, and also the AMELY gene in males, on the Y chromosome. They are involved in amelogenesis, the development of enamel. Amelogenins are type of extracellular matrix protein, which, together with ameloblastins, enamelins and tuftelins, direct the mineralization of enamel to form a highly organized matrix of rods, interrod crystal and proteins.
Enamelin is an enamel matrix protein (EMPs), that in humans is encoded by the ENAM gene. It is part of the non-amelogenins, which comprise 10% of the total enamel matrix proteins. It is one of the key proteins thought to be involved in amelogenesis. The formation of enamel's intricate architecture is thought to be rigorously controlled in ameloblasts through interactions of various organic matrix protein molecules that include: enamelin, amelogenin, ameloblastin, tuftelin, dentine sialophosphoprotein, and a variety of enzymes. Enamelin is the largest protein (~168kDa) in the enamel matrix of developing teeth and is the least abundant of total enamel matrix proteins. It is present predominantly at the growing enamel surface.
Tuftelin is an acidic phosphorylated glycoprotein found in tooth enamel. In humans, the tuftelin protein is encoded by the TUFT1 gene. It is an acidic protein that is thought to play a role in dental enamel mineralization and is implicated in caries susceptibility. It is also thought to be involved with adaptation to hypoxia, mesenchymal stem cell function, and neurotrophin nerve growth factor mediated neuronal differentiation.
Amelogenesis is the formation of enamel on teeth and begins when the crown is forming during the advanced bell stage of tooth development after dentinogenesis forms a first layer of dentin. Dentin must be present for enamel to be formed. Ameloblasts must also be present for dentinogenesis to continue.
Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development. It is inherited in an autosomal dominant pattern, as a result of mutations on chromosome 4q21, in the dentine sialophosphoprotein gene (DSPP). It is one of the most frequently occurring autosomal dominant features in humans. Dentinogenesis imperfecta affects an estimated 1 in 6,000-8,000 people.
Amelogenin, Y isoform is a protein that in humans is encoded by the AMELY gene. AMELY is located on the Y chromosome and encodes a form of amelogenin. Amelogenin is an extracellular matrix protein involved in biomineralization during tooth enamel development.
Amelogenin, X isoform is a protein that in humans is encoded by the AMELX gene. AMELX is located on the X chromosome and encodes a set of isoforms of amelogenin by alternative splicing. Amelogenin is an extracellular matrix protein involved in the process of amelogenesis, the formation of enamel on teeth.
Kallikrein-related peptidase 4 is a protein which in humans is encoded by the KLK4 gene.
Dentin matrix acidic phosphoprotein 1 is a protein that in humans is encoded by the DMP1 gene.
Homeobox protein DLX-3 is a protein that in humans is encoded by the DLX3 gene.
B-cell CLL/lymphoma 9 protein is a protein that in humans is encoded by the BCL9 gene.
Matrix metalloproteinase-20 (MMP-20) also known as enamel metalloproteinase or enamelysin is an enzyme that in humans is encoded by the MMP20 gene.
Dentin sialophosphoprotein is a precursor protein for other proteins found in the teeth. It is produced by cells (odontoblasts) inside the teeth, and in smaller quantities by bone tissues. It is required for normal hardening (mineralisation) of teeth. During teeth development, it is broken down into three proteins such as dentin sialoprotein (DSP), dentin glycoprotein (DGP), and dentin phosphoprotein (DPP). These proteins become the major non-collagenous components of teeth. Their distribution in the collagen matrix of the forming dentin suggests these proteins play an important role in the regulation of mineral deposition. Additional evidence for this correlation is phenotypically manifested in patients with mutant forms of dentin sialophosphoprotein. Such patients suffer dental anomalies including type III dentinogenesis imperfecta.
FAM83H is a protein, which in humans is encoded by the FAM83H gene. The protein is also known as uncharacterized protein FAM83H. FAM83H is targeted for the nucleus. It is predicted to play a role in the structural development and calcification of tooth enamel.
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 as a result of abnormal enamel formation via amelogenesis.
FAM20A is a protein that in humans is encoded by the FAM20A gene.
Kohlschütter-Tönz syndrome (KTS), also called amelo-cerebro-hypohidrotic syndrome, is a rare inherited syndrome characterized by epilepsy, psychomotor delay or regression, intellectual disability, and yellow teeth caused by amelogenesis imperfecta. It is a type A ectodermal dysplasia.
Sodium/potassium/calcium exchanger 4 also known as solute carrier family 24 member 4 is a protein that in humans is encoded by the SLC24A4 gene.
