Figure 4.

Analysis of the amounts of 40S and 60S subunits in wt and mutant yeast strains by centrifugation on low-Mg²⁺ sucrose density gradients. Extracts from isogenic wt (BY47yS5-0) and rpS5 mutant (BY47yS5-13, BY47yS5-24, BY47yS5-30 and BY47yS5-46) strains were resolved by velocity sedimentation on 5–30% sucrose gradients under low Mg²⁺ as described (18). The positions of different ribosomal species are indicated. Right bottom panel shows ribosomal fractions from the BY47yS5-30 strain resolved under high Mg²⁺ concentration (2.5 mM) to indicate the position of the 80S peak on the same gradient. The ratio of the area under the 40S and 60 S peaks is shown (40S : 60S).