FIG. 3.

Effect of erythromycin on assembly in vivo. Methods are described in the legend of Fig. 2, but erythromycin was added to a concentration of 50 μg/ml 10 min before the addition of the ³H pulse-label. A precursor that accumulates sufficiently to be visible in both ¹⁴C-labeled and absorbance profiles is marked by an asterisk. Times of labeling in minutes (and generations) were 1 min 10 s (0.02 generations) (a) and 4 min (0.09 generations) (b). Approximate sedimentation values are given on the plots for material akin to the p₁30S and p₁50S precursors. kcpm, counts per minute (10³).