XpsG, the major pseudopilin in Xanthomonas campestris pv. campestris, forms a pilus-like structure between cytoplasmic and outer membranes.

GspG, -H, -I, -J and -K proteins are members of the pseudopilin family. They are the components required for the type II secretion pathway, which translocates proteins across the outer membrane of Gram-negative bacteria to the extracellular milieu. They were predicted to form a pilus-like structure, and this has been shown for PulG of Klebsiella oxytoca by using electron microscopy.