Fig. 1. Biotinylation of recombinant FimH-FimC complex. (A) Detection of the biotinylated FimH-FimC complex after the proteins were electrophoretically separated and transferred onto a nitrocellulose membrane. Note the detectability of as little as 16 ng of the complex per lane. (B) Competitive binding between the biotinylated and unlabeled FimH-FimC to immobilized -D-mannose. Note that a one-to-one dilution of the biotinylated FimH-FimC with unlabeled protein resulted in 50% reduction in the binding of the labeled protein to immobilized mannose, indicating that the mannose-binding activity of the recombinant protein was not affected by biotinylation. (C) Typical ultrastructure of negatively stained mouse urothelial plaques showing two-dimensional crystals of 16 nm uroplakin particles.