Extracellular Matrix Proteins: Nomenclature and Functions in Biomineralization

Proteins in the extracellular matrix (ECM) of mineralized tissues have specific roles in promoting and/or inhibiting the mineralization processes of collagenous-rich (dentin, cementum, bone) or non-collagenous extracellular matrix components (enamel matrix proteins). These ECM proteins are comprised of two categories of molecules: (1) hydrophobic molecules that define the architecture of the system and the orientation of the crystal growth and (2) the charged molecules that play an active role in initiating, promoting, and regulating crystal formation usually present at the interface of the structural components and the nucleating apatite crystals.