Degrades amelogenin, the major protein component of the enamel matrix and two of the macromolecules characterizing the cartilage extracellular matrix: aggrecan and the cartilage oligomeric matrix protein (COMP). May play a central role in tooth enamel formation. Cleaves aggrecan at the '360-Ser-|-Phe-361' site. Binds 2 Zn(2+) ions per subunit. Binds 2 calcium ions per subunit. Expressed in the enamel organ. The conserved cysteine present in the cysteine-switch motif binds the catalytic zinc ion, thus inhibiting the enzyme. The dissociation of the cysteine from the zinc ion upon the activation-peptide release activates the enzyme. Autoactivates at least at the 105-Asn-|-Tyr-106 site. Belongs to the peptidase M10A family.