Calcified Tissue International

, Volume 51, Issue 3, pp 213–217 | Cite as

The localization and characterization of proteinases for the initial cleavage of porcine amelogenin

  • T. Tanabe
  • M. Fukae
  • T. Uchida
  • M. Shimizu
Laboratory Investigations


In the outermost layer of porcine-developing enamel adjacent to the ameloblasts in the secretory stage, the activities of two proteinases having molecular masses of 76 and 78kDa were detected by enzymography using gelatin as a substrate. On the other hand, high activities of known 30 and 34kDa proteinases were localized in the inner layer of the enamel. The 76kDa proteinase cleaved the carboxylterminal peptide of porcine 25kDa amelogenin to convert it to 20kDa amelogenin. The 78kDa proteinase also acted on the 25kDa amelogenin similarly, but its activity was weak. The results indicate that the 25kDa amelogenin synthesized and secreted by ameloblasts is converted to 20kDa amelogenin by the action of proteinase localized in the outermost layer of the secretory enamel, and then further degraded by the proteinases in the inner layer of the enamel associated with the increase of mineralization.

Key words

Porcine secretory enamel Degradation of amelogenin Proteinases 25kDa amelogenin Enzymography 


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Copyright information

© Springer-Verlag New York Inc. 1992

Authors and Affiliations

  • T. Tanabe
    • 1
    • 2
  • M. Fukae
    • 1
    • 2
  • T. Uchida
    • 1
    • 2
  • M. Shimizu
    • 1
    • 2
  1. 1.Department of Biochemistry, School of Dental MedicineTsurumi UniversityYokohamaJapan
  2. 2.Department of AnatomyYamanashi Medical CollegeYamanashiJapan

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