Dataset Information

Biosynthesis and characterization of rabbit tooth enamel extracellular-matrix proteins.

ABSTRACT: Tooth enamel biomineralization is mediated by enamel proteins synthesized by ameloblast cells. Two classes of proteins have been described: enamelins and amelogenins. In lower vertebrates the absence of amelogenins is believed to give rise to aprismatic enamel; however, rabbit teeth, which apparently do not synthesize amelogenins, form prismatic enamel. The present study was designed to characterize the enamel proteins present in rabbit tooth organs and to gain an insight into the process of biomineralization. Rabbit enamel extracellular-matrix proteins were isolated and characterized during sequential stages of rabbit tooth organogenesis. The biosynthesis of enamel proteins was analysed by metabolic 'pulse-chase' experiments as well as mRNA-translation studies in cell-free systems. Our results indicated that rabbit enamel extracellular matrix contains 'amelogenin-like' proteins. However, these proteins are not synthesized as typical amelogenins, as in other mammalian species, thus suggesting that they are the processing products of higher-molecular-mass precursors. An N-terminal amino acid sequence of 29 residues, considered characteristic of mammalian amelogenins, was present in the rabbit 'amelogenin-like' proteins. By using anti-peptide antibodies to this region, similar epitopes were detected in all nascent enamel proteins, including enamelins. These studies suggest that the N-terminal sequence might be characteristic of all enamel proteins, not only amelogenins.

SUBMITTER: Zeichner-David M

PROVIDER: S-EPMC1149053 | biostudies-other | 1988 May

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:1. Investigations were designed to identify the proteins which characterize the ameloblast phenotype, and to determine to what extent these extracellular-matrix proteins were degraded as a function of enamel matrix mineralization and maturation. 2. The identification of enamel proteins was based on comparisons between the electrophoretic patterns of enamel-containing and non-enamel-containing matrix extracts isolated from specific regions within 26-day embryonic New Zealand White rabbit incisor and molar tooth organs. 3. Since enamel proteins become mineralized on secretion, matrix specimens were demineralized in cold 5% (w/v) trichloroacetic acid, extracted with buffered 6M-urea and reduced with mercaptoethanol, and then the solubilized proteins were fractionated by urea/polyacrylamide-gel electrophoresis. 4. Three enamel-specific electrophoretic components were identified in newly secreted enamel-matrix specimens and this number increased as a function of mineralization and maturation. 5. Antibodies were prepared against embryonic rabbit extracellular matrix containing enamel. Comparison between immunoelectrophoretic patterns demonstrated that two of the three enamel components were antigenic. 6. Polyacrylamide-gel electrophoresis in sodium dodecyl sulphate was used to identify four enamel proteins of mol.wts. (1) 65 000 (2) 58000 (3) 22 000 and (4) 20 000, localized within enamel matrix. Enamel proteins (1) and (3) were phosphorylated, whereas (2) and (4) did not contain detectable phosphate. Labelled proline, leucine, tryptophan and glucosamine were incorporated into each of the four enamel proteins extracted from tooth explants incubated in the presence of radioactive precursors for 6 h. Whereas four proteins were identified in newly secreted enamel matrix, the concentrations of high-molecular-weight proteins (1) and (2) were found to decrease and the number (greater than 10) and concentration of low-molecular-weight polypeptides increased as a function of advanced enamel-matrix mineralization and maturation.

Dataset Information

Biosynthesis and characterization of rabbit tooth enamel extracellular-matrix proteins.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets