Is a promoter of calcium phosphate mineralization, playing a critical role in the formation of the compact, mineralized, aprismatic enamel surface layer during the maturation stage of amelogenesis. Specifically expressed in maturation-stage ameloblasts. Expression increases greatly with the transition from secretory to maturation-stage ameloblasts, is maintained during the maturation stage and gradually declines towards the zone of reduced ameloblasts. Phosphorylated by FAM20C in vitro. O-glycosylated. Belongs to the amelotin family.