Cytochemical and molecular biological study for the molecular diversity of the enamel protein

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Enamel proteins, such as amelogenins and sheath proteins, have several isoforms produced by alternative splicing of mRNAs. In order to clarify the role of molecular diversities of amelogenin proteins in amelogenesis, we have developed region specific antibodies which recognize specific molecular forms. Enamel organ and immature enamel matrix from the porcine tooth germ were analyzed by means of immunochemistry and immunohistochemistry. The results are summarized as follows1. Immunochemical analysis of the immature enamel from the matrix formation stage in the porcine deciduous molar tooth germ showed that the highest molecular weights of proteins stained with antibodies raised against synthetic peptide containing amino acid sequences which correspond amelogenin exons 2-5, 5-6b and 4a were 18 kDa, 6.b kDa and 26 kDa, respectively2. Immunohistochemistry of the matrix formation stage of porcine deciduous molar tooth germ showed that antibodies might reacted with amelogenins containing exons 2-5 stained prism sheath intensely and that exons 5-6b less intensely3. At the differentiation stage, expression of amelogenins translated from exons 2-6b were later than other amelogenins, such as those from exons 5-6b and 6b. On the other hand, at the transition to early maturation stage, disappearance of amelogenins translated from exons 2-5b were latest among the amelogenins examined