| Symbol: | FliG_C |
| FliG C-terminal domain | |
| Pfam: | PF01706 |
| Pfam Clan: | CL0436 |
| Interpro: | IPR000090 |
| Scop: | 1qc7 |
| Symbol: | FliM |
| Flagellar motor switch protein FliM | |
| Pfam: | PF02154 |
| Pfam Clan: | CL0355 |
| Interpro: | IPR001689 |
In molecular biology, the flagellar motor switch protein (Flig) is one of three proteins in certain bacteria coded for by the gene fliG.[1] The other two proteins are FliN coded for by fliN, and FliM coded for by fliM.[2] The protein complex regulates the direction of flagellar rotation and hence controls swimming behaviour.[3] The switch is a complex apparatus that responds to signals transduced by the chemotaxis sensory signalling system during chemotactic behaviour.[3] CheY, the chemotaxis response regulator, is believed to act directly on the switch to induce a switch in the flagellar motor direction of rotation.
The switch complex comprises at least three proteins: FliG, FliM and FliN.[4] It has been shown that FliG interacts with FliM, FliM interacts with itself, and FliM interacts with FliN.[5] Several amino acids 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.[5] 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.[6] 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.[6] [7] FliG is present in about 25 copies per flagellum. The structure of the C-terminal domain of FliG is known, this domain functions specifically in motor rotation.[8]