Flagellar P-ring protein (IPR001782)

Short name: Flag_FlgI

Overlapping homologous superfamilies


Family relationships



The flgH, flgI and fliF genes of Salmonella typhimurium encode the major proteins for the L, P and M rings of the flagellar basal body [PMID: 2544561]. In fact, the basal body consists of four rings (L,P,S and M) surrounding the flagellar rod, which is believed to transmit motor rotation to the filament [PMID: 2129540]. The M ring is integral to the inner membrane of the cell, and may be connected to the rod via the S (supramembrane) ring, which lies just distal to it. The L and P rings reside in the outer membrane and periplasmic space, respectively.

The sequences of the FlgH, FlgI and FliF gene products have been determined [PMID: 2544561]. FlgH and FlgI, which are exported across the cell membrane to their destinations in the outer membrane and periplasmic space, have typical N-terminal cleaved signal-peptide sequences [PMID: 2544561, PMID: 3549691]. FlgH is predicted to have an extensive beta-sheet structure, in keeping with other outer membrane proteins, and FlgI is thought to have even more beta-structure content [PMID: 2544561]. Several aspects of the DNA sequence of these genes and their surrounds suggest complex regulation of the flagellar gene system.

GO terms

Biological Process

GO:0071973 bacterial-type flagellum-dependent cell motility

Molecular Function

GO:0005198 structural molecule activity

Cellular Component

GO:0009428 bacterial-type flagellum basal body, distal rod, P ring
GO:0030288 outer membrane-bounded periplasmic space

Contributing signatures

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