Amelogenin

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Amelogenin is a low-molecular-weight protein found in developing tooth enamel, and it belongs to a family of extracellular matrix (ECM) proteins. Developing enamel contains about 30% protein, and 90% of this is comprised of amelogenins. Although not completely understood, the function of amelogenins is believed to be in organizing enamel rods during tooth development. The latest research indicates that this protein regulates the initiation and growth of hydroxyapatite crystals during the mineralization of enamel. In addition, amelogenins appear to aid in the development of cementum by directing cells that form cementum to the root surface of teeth.

Other significant proteins in enamel are ameloblastins, enamelins, and tuftelins.

The genes for amelogenin can be used in sex determination of samples from unknown human origin through the Polymerase Chain Reaction (PCR). Using primers specific for intron 1 of the gene, the gene sequence for the intron can be amplified. The X chromosome gene, AMELX, gives rise to a 106 bp amplification product (amplicon) and the Y chromosome gene, AMELY, a 112 bp amplicon. Hence, the AMELX contains a 6 bp deletion in the intron 1. Therefore, when the amplicons are run on an agarose gel, samples from male sources (XY) will show two bands on an agarose gel (one for the 106 bp fragment and one for the 112 bp fragment), while females (XX) will show only one band. Thus, this process allows for sex determination of unknown samples.

Mutations in AMELX can cause amelogenesis imperfecta, a disorder of tooth enamel development.