Has a major role in enamel formation. Required during the maturation stage of tooth development for clearance of enamel proteins and normal structural patterning of the crystalline matrix. In developing teeth, expressed in ameloblasts during transition and maturation stages (PubMed:10863090, PubMed:10690663, PubMed:19578120). Expressed weakly in odontoblasts (PubMed:10863090). Not detected in odontoblasts (PubMed:19578120). Detected in the epithelium surrounding the erupted first molar (PubMed:10690663). N-glycosylated. The N-glycan structures are of complex diantennary or triantennary type, which may be further modified with up to 2 sialic acid residues. Viable and fertile, when reared on a soft diet. Tooth morphology is grossly normal but the enamel surface is fragile and rapidly abraded. Although formation of the enamel layer is initially normal, the crystallites fail to thicken and interlock. The enamel proteins enamelin and amelogenin are not cleared and persist in the matrix during the maturation stage. Belongs to the peptidase S1 family. Kallikrein subfamily.