Flagellar motor switch protein FliG (IPR000090)

Short name: Flg_Motor_Flig

Overlapping homologous superfamilies


Family relationships



The flagellar motor switch in Escherichia coli and Salmonella typhimurium regulates the direction of flagellar rotation and hence controls swimming behaviour [PMID: 8224881]. The switch is a complex apparatus that responds to signals transduced by the chemotaxis sensory signalling system during chemotactic behaviour [PMID: 8224881]. CheY, the chemotaxis response regulator, is believed to act directly on the switch to induce tumbles in the swimming pattern, but no physical interactions of CheY and switch proteins have yet been demonstrated.

The switch complex comprises at least three proteins - FliG, FliM and FliN. It has been shown that FliG interacts with FliM, FliM interacts with itself, and FliM interacts with FliN [PMID: 8631704]. Several residues within the middle third of FliG appear to be strongly involved in the FliG-FliM interaction, with residues near the N- or C-termini being less important [PMID: 8631704]. Such clustering suggests that FliG-FliM interaction plays a central role in switching.

Analysis of the FliG, FliM and FliN sequences shows that none are especially hydrophobic or appear to be integral membrane proteins [PMID: 2656645]. This result is consistent with other evidence suggesting that the proteins may be peripheral to the membrane, possibly mounted on the basal body M ring [PMID: 2656645, PMID: 1631122]. FliG is present in about 25 copies per flagellum.

GO terms

Biological Process

GO:0071973 bacterial-type flagellum-dependent cell motility
GO:0006935 chemotaxis

Molecular Function

GO:0003774 motor activity

Cellular Component

GO:0009288 bacterial-type flagellum

Contributing signatures

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