This is a prokaryotic family that contains proteins of the FliH and HrpE/YscL family. These proteins are involved in type III secretion, which is the process that drives flagellar biosynthesis and mediates bacterial-eukaryotic interactions [1-2]. This family also V-type ATPase subunit E. This subunit appears to form a tight interaction with subunit G in the F0 complex [3]. Subunits E and G may act together as stators to prevent certain subunits from rotating with the central rotary element [3]. Pfam:PF01991 also contains V-type ATPase subunit E proteins.

1: The complete hrp gene cluster of Pseudomonas syringae pv. syringae 61 includes two blocks of genes required for harpinPss secretion that are arranged colinearly with Yersinia ysc homologs. Huang HC, Lin RH, Chang CJ, Collmer A, Deng WL; Mol Plant Microbe Interact 1995;8:733-746. PMID:7579617

2: Evolutionary links between FliH/YscL-like proteins from bacterial type III secretion systems and second-stalk components of the FoF1 and vacuolar ATPases. Pallen MJ, Bailey CM, Beatson SA; Protein Sci. 2006;15:935-941. PMID:16522800

3: Building the stator of the yeast vacuolar-ATPase: specific interaction between subunits E and G. Fethiere J, Venzke D, Diepholz M, Seybert A, Geerlof A, Gentzel M, Wilm M, Bottcher B; J Biol Chem. 2004;279:40670-40676. PMID:15292229