FIG. 5.

Phosphorylation of DrrB and DrrB-N induces dimerization. Size exclusion chromatography of DrrB proteins in the presence and absence of phosphoramidate was carried out with a Superdex 75 column as described in Materials and Methods. The column was calibrated (A) with albumin (66 kDa), ovalbumin (44 kDa), trypsin inhibitor (21 kDa), and RNase A (13.7 kDa) as molecular mass standards. (A) Profile of full-length DrrB and phosphorylated DrrB, which eluted at positions corresponding to molecular masses of 22.2 and 42.1 kDa, respectively. (B) Profile of DrrB-N and phosphorylated DrrB-N, which migrated with apparent molecular masses of 13.8 and 27.9 kDa, respectively.