FIG. 4.

Saliva degrades purified integrin α5β1 and α1β1, but not αvβ3 or αvβ5: Effects of inhibitors. In (A) purified integrins αvβ3 or αvβ5 were incubated with saliva overnight at 37°C in EBM-2 and no degradation was observed after SDS/PAGE and staining with 0.2% Coomassie blue (n = 5). In (B) purified integrins α5β1 and α1β1 were incubated with saliva as in (A) and degradation was observed for both α and β chains after SDS/PAGE and staining as above. (C) The metalloprotease inhibitors EDTA (20 mM) or 1,10-phenanthroline (2.5 mM), and the serine protease inhibitor PMSF (2.5 mM) were incubated for 30-min with saliva followed by addition of integrin α5β1 and overnight incubation as in (A) followed by SDS/PAGE and staining as above. The gel shows that degradation of α5β1 did not occur when saliva was treated with EDTA or 1,10-phenanthroline, but was observed in the presence of PMSF (n=4). Results are from a typical experiment.