The influences of serine and CheW on methylation. The enlarged representation of the methylation region from one Tsr subunit in panel A illustrates the locations relative to the N and C-termini of Tsr (N and C), and the cytoplasmic domain hairpin (at bottom). For simplicity, all other representations depict (panels B to D) show only the two methylation helices. Numbers next to the four sites are relative rates (r); not in parentheses are rates relative to the rate without ligand (r = v+ligand(s)/vno ligand). The r-values in parentheses are the rates at various sites (v
) relative to the rate at site four (v4) under the same conditions (r = v
/v4). A: no ligand;B: 500 μM serine; C: 60 μM CheW; D: both serine and CheW.