Differences between non-collagenous protein content of rat incisor and permanent bovine dentin

The content of non-collagenous proteins, extractable upon demineralization, in dentin from permanent bovine teeth and continuously growing rat incisors was compared. In both tissues, highly phosphorylated phosphoprotein and proteoglycan were major non-collagenous components. Whereas gamma-carboxyglutamate-containing proteins of the osteocalcin type constituted a major fraction in rat dentin, these were virtually absent from bovine dentin. The two tissues differed in content and composition of phosphoproteins, the major non-collagenous protein fraction of dentin. Considerable differences were also found in the presence of other acidic non-collagenous proteins. It was concluded that the general non-collagenous protein composition of dentin from different species may differ fundamentally, but that such differences may be advantageous in exploring the different roles of specific components in the mechanism of biomineralization.