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. 2000 Mar;182(5):1437–1441. doi: 10.1128/jb.182.5.1437-1441.2000

FIG. 3.

FIG. 3

FIG. 3

Citrate-sensing abilities of the Cys-replaced Tcp receptors. (A) Temporal stimulation assay of cells expressing the Cys-replaced Tcp receptors. HCB339 (ΔMCP) cells expressing wild-type or mutant Tcp as the sole chemoreceptor were treated with 15% glycerol and then stimulated with various concentrations of citrate. The fraction of smooth-swimming cells after 30 s was measured at 25°C as described previously (31). Symbols: open circles, wild-type Tcp; closed circles, Tcp-R63C; open triangles, Tcp-R68C; closed triangles, Tcp-R72C; open squares, Tcp-K75C; closed squares, Tcp-R78C; open diamonds, Tcp-Y150C; closed diamonds, Tcp-K157C. (B) Immunoblotting analysis of methylation patterns of the Cys-replaced Tcp receptors. HCB339 (ΔMCP) cells expressing wild-type or mutant Tcp were incubated with 15% glycerol (Glyc), distilled water (None), 10 mM citrate (Cit-10), or 50 mM citrate (Cit-50) at 25°C for 30 min. Samples were subjected to SDS-PAGE followed by immunoblotting with anti-Tsr serum (18), which cross-reacts with Tcp, as described previously (32).