Tuftelin--aspects of protein and gene structure.

The acidic enamel protein tuftelin has now been cDNA cloned, sequenced and characterized in a number of vertebrate species. Recently, the bovine tuftelin gene structure was elucidated. Cloning of the human tuftelin gene and partial sequencing of a number of exons have also been achieved. Immunologically, the protein has been shown to be conserved throughout 550 million years of vertebrate evolution. The gene has been localized to the long arm of the autosomal chromosome 1. The mapping of the human tuftelin gene to a well-defined cytogenetic region could be important in understanding the etiology of autosomally inherited amelogenesis imperfecta, the most common hereditary disease of enamel. The present paper reviews the primary structure, mRNA/cDNA structure, and gene structure of tuftelin. It describes its immunolocalization at the light microscope level and at the ultrastructural level in both the ameloblast cells and in the extracellular enamel matrix. The timing of tuftelin expression and its possible roles in enamel formation are discussed.