1.7 - 2.0 µM
||Sourjik V, Berg HC. Binding of the Escherichia coli response regulator CheY to its target measured in vivo by fluorescence resonance energy transfer. Proc Natl Acad Sci U S A. 2002 Oct 1 99(20):12669-74. p.12670 left column bottom paragraphPubMed ID12232047
|| Tang H, Blair D F (1995) Regulated underexpression of the FliM protein of Escherichia coli and evidence for a location in the flagellar motor distinct from the MotA/MotB torque generators. J Bacteriol 177: 3485–3495.  Zhao R, Amsler C D, Matsumura P, Khan S (1996) FliG and FliM distribution in the Salmonella typhimurium cell and flagellar basal bodies. J Bacteriol 178: 258–265.PubMed ID7768858, 8550426
||P.12669 left column bottom paragraph: "To learn more about the binding of CheY∼P to FliM and about the kinetics of the chemotactic response, [investigators] extended [their] recent analysis of phosphorylation-dependent interactions of CheY with CheZ (ref 9) and measured fluorescence resonance energy transfer (FRET) between cyan fluorescent protein (CFP) fused to the N terminus of FliM (CFP-FliM) and yellow fluorescent protein (YFP) fused to the C terminus of CheY (CheY-YFP). The FRET technique relies on the distance-dependent transfer of energy from an excited donor fluorophore (CFP) to an acceptor fluorophore (YFP) and allows one to monitor changes in protein interactions in real time in vivo (refs 10, 11)."
||p.12670 left column bottom paragraph: "The level of expression of CFP-FliM in [investigators'] standard experiment, necessary for optimum complementation of motility, was about three times higher than the level of FliM in the wild type (1.7–2.0 μM primary sources)." Primary sources  &  investigated E. coli & S. typhimurium, respectively.