FIG. 2.

Expression by the T7 RNA polymerase system and purification of the Rci protein. E. coli BL21(DE3) cells harboring pET11a (lanes 1 and 2) or pETrci (lanes 3 and 4) were grown in M9 medium and treated with 0.4 mM IPTG (lanes 2 and 4) or untreated (lanes 1 and 3). The proteins were analyzed by SDS-PAGE followed by staining with Coomassie brilliant blue. Lane M, marker proteins; lanes 1 to 4, total cell protein; lane 5, soluble proteins of IPTG-induced cells harboring pETrci; lane 6, peak fraction of phosphocellulose column chromatography; lane 7, peak fraction of gel filtration chromatography. The numbers on the left indicate the molecular masses of marker proteins. The location of the Rci protein is indicated.