Amelogenin, X isoform is a form of amelogenin found on the X chromosome. Amelogenin X is a member of the amelogenin family of extracellular matrix proteins. When alternative splicing occurs it results in multiple transcript variants encoding different isoforms.

Amelogenins are highly conserved proteins secreted by ameloblasts, and constitute 90% of the enamel organic matrix. As the proteins are digested and removed, the mineral crystals grow in well-organized prism patterns . The sequences were homologous to previously sequenced cDNA clones of mouse and cattle encoding amelogenin. Three exons were identified in both the X and the Y sequences.