Type III secretion system FHIPEP (IPR001712)

Short name: T3SS_FHIPEP

Overlapping homologous superfamilies


Family relationships


The Flagellar/Hr/Invasion Proteins Export Pore (FHIPEP) family [PMID: 8253684, PMID: 8316211] consists of a number of proteins that constitute the type III secretion (or signal peptide-independent) pathway apparatus [PMID: 1365398, PMID: 1592799]. This mechanism translocates proteins lacking an N-terminal signal peptide across the cell membrane in one step, as it does not require an intermediate periplasmic process to cleave the signal peptide. It is a common pathway amongst Gram-negative bacteria for secreting toxic and flagellar proteins.

The pathway apparatus comprises three components: two within the inner membrane and one within the outer [PMID: 8316211]. An FHIPEP protein is located within the inner membrane, although it is unknown which component it constitutes. FHIPEP proteins have all about 700 amino-acid residues. Within the sequence, the N terminus is highly conserved and hydrophobic, suggesting that this terminus is embedded within the membrane, with 6-8 transmembrane (TM) domains, while the C terminus is less conserved and appears to be devoid of TM regions. It is possible that members of the FHIPEP family serve as pores for the export of specific proteins.

Characterized proteins from the FHIPEP family include: the flagellar biosynthesis protein FlhA which is required for formation of the rod structure of the flagellar apparatus [PMID: 8002587]; and the secretion system apparatus protein SsaV from Salmonella typhimurium which is required for the secretion of the SpvB toxin [PMID: 18248436].

GO terms

Biological Process

GO:0009306 protein secretion

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0016020 membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.