Tuft protein: protein cross-linking in enamel development

Robinson C, Hudson J. Tuft protein: protein cross‐linking in enamel development. Eur J Oral Sci 2011; 119 (Suppl. 1): 50–54. © 2011 Eur J Oral Sci Tuft protein is a material associated with enamel tufts, and resides in dental enamel primarily at the enamel–dentine junction. It is located primarily at prism peripheries and extends in a very attenuated form towards the enamel outer surface. While it appears to be a mixture of components, partial sequencing and antibody studies have demonstrated the presence of amelin, a protein associated with prism boundaries. Biochemical investigations have been seriously hampered by the fact that tuft protein is extremely insoluble in a range of solvents, including mineral acids, EDTA, chaotropic agents, and detergents including SDS. This raised the question as to whether it could be chemically cross‐linked. Antibodies to γ‐glutamyl cross‐linking peptide were used to determine the presence of a cross‐linking isopeptide. In all cases examined, a positive response indicated that tuft protein does display chemical cross‐linking, which may explain the insoluble nature of this material. This may be a mechanism to prevent protein degradation at the enamel–dentine junction during the degradation of enamel matrix, which occurs during amelogenesis.