| First Author | Geng S | Year | 2015 |
| Journal | J Biol Chem | Volume | 290 |
| Issue | 34 | Pages | 20661-73 |
| PubMed ID | 26070558 | Mgi Jnum | J:225436 |
| Mgi Id | MGI:5693313 | Doi | 10.1074/jbc.M115.640185 |
| Citation | Geng S, et al. (2015) Protein Interaction between Ameloblastin and Proteasome Subunit alpha Type 3 Can Facilitate Redistribution of Ameloblastin Domains within Forming Enamel. J Biol Chem 290(34):20661-73 |
| abstractText | Enamel is a bioceramic tissue composed of thousands of hydroxyapatite crystallites aligned in parallel within boundaries fabricated by a single ameloblast cell. Enamel is the hardest tissue in the vertebrate body; however, it starts development as a self-organizing assembly of matrix proteins that control crystallite habit. Here, we examine ameloblastin, a protein that is initially distributed uniformly across the cell boundary but redistributes to the lateral margins of the extracellular matrix following secretion thus producing cell-defined boundaries within the matrix and the mineral phase. The yeast two-hybrid assay identified that proteasome subunit alpha type 3 (Psma3) interacts with ameloblastin. Confocal microscopy confirmed Psma3 co-distribution with ameloblastin at the ameloblast secretory end piece. Co-immunoprecipitation assay of mouse ameloblast cell lysates with either ameloblastin or Psma3 antibody identified each reciprocal protein partner. Protein engineering demonstrated that only the ameloblastin C terminus interacts with Psma3. We show that 20S proteasome digestion of ameloblastin in vitro generates an N-terminal cleavage fragment consistent with the in vivo pattern of ameloblastin distribution. These findings suggest a novel pathway participating in control of protein distribution within the extracellular space that serves to regulate the protein-mineral interactions essential to biomineralization. |
