Localization of enamel proteins : an electron microscopic immunocytochemical study using antibodies against synthetic peptides.

采用免疫化学和免疫细胞化学方法对猪和大鼠的未成熟牙釉质进行了免疫化学和免疫细胞化学研究。结果总结如下：1。最初分泌的25 kDa的淀粉原蛋白优先定位于未成熟牙釉质的表层，并被降解产生20 kDa和其他分子量较低的淀粉原蛋白，这些淀粉原蛋白存在于未成熟牙釉质的深层。20 kDa淀粉原蛋白降解产生的6-7 kDa淀粉原蛋白（含有25 kDa淀粉原蛋白残基1-45的n端片段）很少出现在表层，主要分布在深层，特别是在未成熟釉的杆鞘中。89 kDa的釉素从成釉细胞分泌出来后，定位于杆状和杆状牙釉质中，其降解速度比25 kDa的釉原蛋白快。一些由89 kDa的搪瓷素降解产生的n端低分子量肽可能集中在杆鞘中。杆状鞘主要由一种新的搪瓷蛋白家族组成，即杆状鞘蛋白，不同于淀粉原蛋白或搪瓷蛋白。然后将降解的淀粉原蛋白和搪瓷素添加到杆鞘中。最初分泌的杆状鞘蛋白分子量估计为30-40 kDa，可能比25 kDa的淀粉原蛋白降解得更快。大鼠门牙和磨牙的未成熟牙釉质中没有棒状鞘，这表明大鼠的成釉发育可能与猪和人有所不同。32 kDa的非成釉蛋白可能是140 kDa和/或89 kDa蛋白的降解产物，这两种蛋白都存在于棒和棒间牙釉质中，可能在成釉发生的初始钙化和晶体生长调节中起重要作用。

Immature enamel of the pig and the rat were investigated immunochemically and immunocytochemically using antibodies against synthetic peptide fragments of porcine enamel proteins. The results are summarized as follows.1. Originally secreted amelogenin, the 25 kDa amelogenin, is preferentially localized in the surface layer of immature enamel and is degraded to produce 20 kDa and other lower molecular weigh amelogenins which are found in deeper layer of the immature enamel.2. The 6-7 kDa amelogenin ( N-terminal segment containing residues 1-45 of the 25 kDa amelogenin) produced by degradation of the 20 kDa amelogenins were rarely found in surface layer and were predominantly localized in deep layer, especially in the rod sheath of immature enamel.3. The 89 kDa enamelin is localized in rod and interrod enamel just after its secretion from the ameloblast and is degraded faster than the 25 kDa amelogenin. Some N-terminal low molecular weight peptides produced by degradation of the 89 kDa enamelin may be concentrated in the rod sheaths.4. The rod sheaths are primarily composed of a new category of enamel protein family, the rod sheath proteins, different from the amelogenins or enamelins. Degraded amelogenins and enamelins are then added to the rod sheaths. Molecular weights of originally secreted rod sheath proteins are estimated 30-40 kDa and may be degraded faster than the 25 kDa amelogenin.5. The rod sheaths are absent from the immature enamel of rat incisors and molars, indicating the amelogenesis of the rat may somewhat differ from that of pig and man.6. The 32 kDa nonamelogenin protein is likely to be a degradation product of the 140 kDa and/or 89 kDa proteins, both of which are present in the rod and interrod enamel and may play a significant role in the initial calcification and crystal growth regulation in the amelogenesis.