Ameloblast differentiation: protein synthesis and secretion in fetal New Zealand white rabbit molar tooth organs and isolated epithelia "in vitro".

We have attempted in this preliminary communication to determine the kinetic behaviour pf intracellular and extracellular forms of secretory ameloblast proteins. Our experimental strategy assumes several intracellular forms of enamel proteins: preproenamel leads to proenamel leads to enamel protein (1) leads to enamel protein (2) leads to enamel protein (3) leads to etc. Intracellular preproenamel has a molecular weight of greater than 70,00 and is selectively inhibited by 6 micronM - 12 micronM proflavine. Synthesis and secretion requires 30 minutes in vitro. Secretory ameloblasts in vitro synthesize and secrete a number of proteins ranging from 94,000 daltons to 10,000 daltons. Isotopically-labeled leucine, cystine, proline, methionine and an amino acid mixture were all found to be incorporated into enamel proteins. Preliminary data with protease inhibitors indicates that an enamel protease is directly involved in proenamel leads to enamel protein processing.