Figure 6.

Effect of FtsY or Ffh depletion in an isogenic background on the cellular distribution of ribosomes. (A) E. coli HA101 cultures were grown with or without arabinose (for induction of FtsY) or anhydrotetracycline (for induction of Ffh), and the growth was monitored by measuring the optical density of the cultures when indicated. (B) After 3 hr, samples were withdrawn, and cells were fractionated as described for Fig. 1. Lane 5 represents samples that were taken from cells grown without arabinose and anhydrotetracycline for 3 hr and then induced with anhydrotetracycline for 1.5 hr. Total extracts (20 μg of proteins) were separated by SDS/PAGE and subjected to Western blotting with anti-FtsY and anti-Ffh antibodies. After flotation, identical aliquots from the interface fractions (membrane ribosomes, MR) were probed with antibodies against the ribosomal protein L9.