Cleavage site specificity of MMP-20 for secretory-stage ameloblastin

Y. H.P. Chun, Y. Yamakoshi, F. Yamakoshi, M. Fukae, J. C.C. Hu, J. D. Bartlett, J. P. Simmer

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Ameloblastin is processed by protease(s) during enamel formation. We tested the hypothesis that MMP-20 (enamelysin) catalyzes the cleavages that generate secretory-stage ameloblastin cleavage products. We isolated a 23-kDa ameloblastin cleavage product from developing enamel and determined its N-terminus sequence. Ameloblastin was stably expressed and secreted from HEK293-H cells, purified, and digested with MMP-20 or Klk4 (kallikrein 4). The digests were analyzed by SDS-PAGE and Western blotting, and cleavage products were characterized by N-terminal sequencing. Six fluorescent peptides were digested with MMP-20 and Klk4 and analyzed by RP-HPLC and by mass spectrometry. MMP-20 cleaved each peptide exactly at the sites corresponding to ameloblastin cleavages catalyzed in vivo. Klk4 cleaved ameloblastin and the fluorescent peptides at sites not observed in vivo, and cleaved at only a single correct site: before Leu171. We conclude that MMP-20 is the enzyme that processes ameloblastin during the secretory stage of amelogenesis, and we present a hypothesis about the sequence of ameloblastin cleavages.

Original languageEnglish (US)
Pages (from-to)785-790
Number of pages6
JournalJournal of dental research
Issue number8
StatePublished - Aug 2010


  • enamel
  • fluorescent peptides
  • proteases
  • tooth

ASJC Scopus subject areas

  • Dentistry(all)


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