The periplasmic linker protein component of an inducible organic solvent efflux pump. Involved in export of toluene and styrene but not of m-xylene, propylbenzene or ethylbenzene. Is not involved in antibiotic or AMP efflux. The ttgDEF operon is induced in the presence of toluene and styrene, but not m-xylene. Belongs to the membrane fusion protein (MFP) (TC 8.A.1) family. Extended N-terminus. Truncated N-terminus.