(A) SDS gel of purified proteins; lanes: 1, protein marker; 2, HPr kinase(His)6; 3, HPr(His)6; and 4, Crh(His)6. (B) Phosphorylation of HPr or Crh by purified HPr kinase; lanes: 1, 1 μg of HPr kinase(His)6; 2, 1 μg of HPr kinase(His)6 with HPr(His)6; 3, HPr(His)6; 4, 1 μg of HPr kinase(His)6 with Crh(His)6; and 5, Crh(His)6. (C) Effect of 20 mM FBP on the phosphorylation of 1 μg HPr(His)6; only samples loaded on lanes with even numbers contained FBP; lanes 1 and 2 contained 0.5 ng; lanes 3 and 4, 5 ng; lanes 5 and 6, 50 ng; lanes 7 and 8, 250 ng; and lanes 9 and 10, 750 ng of HPr kinase(His)6.