Plays a role in virulence. Not detected in flagellar preparations, requires the flagellar export apparatus (FlgF) for secretion. (Microbial infection) Binds to the surface of human HEp2 (ATCC CCL-23) cells. The secreted form is about 1 kDa larger than the whole cell lysate form, presumably due to post-translational modification. A 22 kDa form is also found in the secreted fraction, probably resulting from proteolysis. No visible effect on flagellar structure, cell shape or motility. Adheres to host epithelial cells (human HEp2) but invades less well (14% suriving bacteria, determined by bacterial counts from lysed cells after 2 hours of gentamicin treatment).