This family consists of several enterobacterial PilO proteins. The function of PilO is unknown although it has been suggested that it is a cytoplasmic protein in the absence of other Pil proteins, but PilO protein is translocated to the outer membrane in the presence of other Pil proteins. Alternatively, PilO protein may form a complex with other Pil protein(s). PilO has been predicted to function as a component of the pilin transport apparatus and thin-pilus basal body [1]. This family does not seem to be related to Pfam:PF04350.

1: Genes required for plasmid R64 thin-pilus biogenesis: identification and localization of products of the pilK, pilM, pilO, pilP, pilR, and pilT genes. Sakai D, Komano T; J Bacteriol 2002;184:444-451. PMID:11751821