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

釉蛋白，如釉原蛋白和鞘蛋白，具有通过mRNA的选择性剪接产生的几种同种型。为了阐明釉原蛋白的分子结构在釉质形成中的作用，我们开发了识别特定分子形式的区域特异性抗体。采用免疫组化和免疫组织化学方法对猪牙胚釉器官和未成熟釉基质进行了分析。结果总结如下1.对猪乳磨牙牙胚中基质形成阶段的未成熟釉质的免疫化学分析表明，用针对含有对应于釉原蛋白外显子2-5、5- 6 b和4a的氨基酸序列的合成肽的抗体染色的蛋白质的最高分子量分别为18 kDa、6.b kDa和26 kDa 2。猪乳磨牙牙胚基质形成期的免疫组化结果显示，抗体可与含有外显子2-5的釉原蛋白强烈反应，而外显子5- 6 b反应较弱3。在分化阶段，外显子2- 6 b翻译的釉原蛋白的表达晚于其他釉原蛋白，如外显子5- 6 b和6 b。另一方面，在向早期成熟阶段的过渡中，在检测的釉原蛋白中，从外显子2- 5 b翻译的釉原蛋白的消失是最晚的

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