Ameloblastin

Ameloblastin, encoded by the AMBN gene, is a secreted enamel matrix protein produced by ameloblasts during the secretory stage of tooth development. Along with amelogenin and enamelin, ameloblastin is a component of the organic enamel matrix, though it is less abundant than amelogenin. The protein is synthesized with a signal peptide and is secreted into the extracellular matrix, where it becomes part of the matrix that supports enamel prism formation.

During enamel development, ameloblastin undergoes proteolytic processing by enamel-specific proteases such as MMP20 and KLK4, generating fragments that remain associated with the matrix through maturation.

Functionally, ameloblastin is believed to contribute to cell–matrix adhesion, organize the enamel matrix, and influence ameloblast differentiation and movement. Its presence helps maintain the integrity of the enamel organ and supports proper enamel prism patterning.

Genetic variants in AMBN have been associated with amelogenesis imperfecta in humans, a condition featuring defective enamel formation. In animal models, absence of ameloblastin leads to enamel defects, including hypoplasia and abnormal ameloblast morphology, underscoring its importance in enamel biomineralization.

Ameloblastin interacts with other enamel matrix proteins and binds to hydroxyapatite, helping to coordinate mineral deposition within the forming enamel.