YadA but not Myf is degraded by gut proteases. Y. enterocolitica WA-314 (wt), yadA mutant (yadA) or Δmyf mutant were digested with small intestinal (SI) luminal fluid, α-chymotrypsin (CT), trypsin (T), carboxypeptidase A (CP), pepsin (P), elastase (E) or trypsin digestion buffer (control) for 2 h at 37°C. SI was washed with 2 ml PBS centrifuged and supernatant was used for digests. 1 × 107 CFU yersiniae were subjected to Western blotting with a polyclonal YadA (a) or Myf (b) antibody. Solid arrowheads point to full length YadA, open arrowheads point to specific YadA degradation products.