ameloblastin


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ameloblastin

A minor protein of the enamel matrix encoded by AMBN on chromosome 4q21 that is expressed by ameloblasts during the differentiation of inner enamel epithelium, which may be a growth factor for periodontal ligament cells, facilitating their attachment. Ameloblastin modulates bone morphogenetic protein expression and downregulates collagen-1 expression.
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[43], based on previously reported cross-reactivity of antibodies to gliadin with the enamel proteins, amelogenin and ameloblastin, investigated the ability of anti-gliadin IgG to recognize enamel organ structures.
(17) Among the secreted proteins are first those of the extracellular matrix (amelogenin, ameloblastin, and enamelin) and secondly the proteases: metalloproteinase matrix 20 (MMP-20) and kallikrein 4 (KLK-4).
Inorganic component mostly comprises hydroxyapatite (HAp) which has a chemical formula Ca10(PO4)6(OH)2 (calcium hydroxyapatite).1 Organic part comprises proteins, mainly amelogenin, ameloblastin and tuftelin, with traces of proteoglycans and lipoids which mostly disappear upon enamel maturation.
A transgenic animal model resembling amelogenesis imperfecta related to ameloblastin overexpression.
Genes implicated in autosomal forms are genes encoding enamel matrix proteins namely: enamelin and ameloblastin tuftelin MMP-20 and kallikrein 4.
Association between ameloblastin gene polymorphisms and the susceptibility to dental Fluorosis.
Cleavage site specificity of MMP-20 for secretory-stage ameloblastin. J Dent Res 2010;89:785-90.
For example a second locus for X-linked recessive AI, (AIH3) has been mapped to chromosome Xq24-q27.1 Similarly, an autosomal dominant, local hypoplastic form of AI, (AIH2) has been mapped to a 4mb region of human chromosome 4q11-q21 that encompasses the gene encoding the amleoblast specific protein ameloblastin, AMBN.
The major protein components of the enamel matrix include the most abundant amelogenin proteins as well as less plentiful proteins such as enamelin and ameloblastin. The enamel defect in amelogensis imperfecta (AI) generally results in enamel that is too thin (hypoplastic) or too soft (hypocalcification or hypomaturation).
Secretory-stage ameloblasts are responsible for many important processes necessary for enamel formation, including: alternative mRNA splicing, translation and secretion of enamel proteins (amelogenin, ameloblastin, enamelin, MMP-20), selective reabsorption and degradation of cleavage products, establishment and regulation of the influx of calcium and phosphate ions, and maintenance of extracellular pH and ionic strength (Simmer & Fincham, 1995; Fincham et al., 1999).