Ameloblastin

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]

AMBN
Identifiers
AliasesAMBN, AI1F, Sheathlin, ameloblastin
External IDsOMIM: 601259 MGI: 104655 HomoloGene: 7625 GeneCards: AMBN
Orthologs
SpeciesHumanMouse
Entrez

258

11698

Ensembl

ENSG00000178522

ENSMUSG00000029288

UniProt

Q9NP70

O55189

RefSeq (mRNA)

NM_016519

NM_009664
NM_001303431

RefSeq (protein)

NP_057603

NP_001290360
NP_033794

Location (UCSC)Chr 4: 70.59 – 70.61 MbChr 5: 88.6 – 88.62 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Function

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.

Clinical significance

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]

References
  1. GRCh38: Ensembl release 89: ENSG00000178522 - Ensembl, May 2017
  2. GRCm38: Ensembl release 89: ENSMUSG00000029288 - Ensembl, May 2017
  3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. "Entrez Gene: Ameloblastin (enamel matrix protein)".
  6. Hu JC, Chun YH, Al Hazzazzi T, Simmer JP (2007). "Enamel formation and amelogenesis imperfecta". Cells Tissues Organs. 186 (1): 78–85. doi:10.1159/000102683. PMID 17627121. S2CID 28367304.
  7. Pandya M, Diekwisch TG (December 2021). "Amelogenesis: Transformation of a protein-mineral matrix into tooth enamel". Journal of Structural Biology. 213 (4): 107809. doi:10.1016/j.jsb.2021.107809. PMC 8665087. PMID 34748943.
  8. Bartlett JD (September 2013). "Dental enamel development: proteinases and their enamel matrix substrates". ISRN Dentistry. 2013: 684607. doi:10.1155/2013/684607. PMC 3789414. PMID 24159389.
  9. Poulter JA, Murillo G, Brookes SJ, Smith CE, Parry DA, Silva S, et al. (October 2014). "Deletion of ameloblastin exon 6 is associated with amelogenesis imperfecta". Human Molecular Genetics. 23 (20): 5317–5324. doi:10.1093/hmg/ddu247. PMC 4168819. PMID 24858907.

Further reading
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