Members of this protein family are part of the machinery of bacterial type III secretion in a number of bacteria that target animal cells. In the well-studied system from Yersinia, a complex of this protein (SycN) and YscB acts as a chaperone for the export of YopN []. YopN then acts to control effector protein secretion, in response to calcium levels, so that secretion occurs only after contact with the targeted eukaryotic cell.
Members of this family include YscB of Yersinia and functionally equivalent (but differently named) proteins from type III secretion systems of other pathogens that affect animal cells. In Yersinia pestis, the secretion of effector proteins, termed Yersinia outer proteins (Yops), is regulated by the activity of the YopN/SycN/YscB/TyeA complex. YscB acts, along with SycN (), as a chaperone for YopN, a key part of a complex that regulates type III secretion so that it responds to contact with the eukaryotic target cell [, ].
