Amelogenin, X isoform is a protein that in humans is encoded by the ''AMELX''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. 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: protei ...
.
AMELX is located on the
X chromosome
The X chromosome is one of the two sex chromosomes in many organisms, including mammals, and is found in both males and females. It is a part of the XY sex-determination system and XO sex-determination system. The X chromosome was named for its u ...
and encodes a set of isoforms of
amelogenin
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 develo ...
by
alternative splicing
Alternative splicing, alternative RNA splicing, or differential splicing, is an alternative RNA splicing, splicing process during gene expression that allows a single gene to produce different splice variants. For example, some exons of a gene ma ...
.
Amelogenin is an
extracellular matrix
In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...
protein involved in the process of
amelogenesis, the formation of
enamel on teeth.
Function
AMELX is involved in
biomineralization
Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often resulting in hardened or stiffened '' mineralized tissues''. It is an extremely widespread phenomenon: all six taxonomic kingd ...
during
tooth enamel
Tooth enamel is one of the four major Tissue (biology), 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 (tooth), crown. The other ...
development.
The ''AMELX'' gene encodes for the structural modeling protein, amelogenin, which works with other amelogenesis-related proteins to direct the mineralisation of enamel. This process involves the organization of
enamel rods, the basic unit of tooth enamel, as well as the inclusion and growth of
hydroxyapatite
Hydroxyapatite (International Mineralogical Association, IMA name: hydroxylapatite) (Hap, HAp, or HA) is a naturally occurring mineral form of calcium apatite with the Chemical formula, formula , often written to denote that the Crystal struc ...
crystals.
Clinical significance
Mutations in ''AMELX'' result in
amelogenesis imperfecta
Amelogenesis imperfecta (AI) is a congenital disorder which presents with a rare abnormal formation of the Tooth enamel, enamel or external layer of the crown of teeth, unrelated to any systemic or generalized conditions. Enamel is composed mostly ...
.
It has been shown that mice with a
knocked-out ''AMELX'' gene will present disorganized and hypoplastic enamel.
See also
*
AMELY
References
External links
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Genes on human chromosome X
Human proteins
{{Gene-X-stub