FIG. 3.

The npa2-1 mutation and the depletion of Npa2p result in a deficit in free 60S r-subunits and in the accumulation of half-mer polysomes. W303-1B (NPA2) (A) and IVY251 (npa2-1) (B) strains were grown in YPD at 30°C. Strain YH378 (GAL::ZZ-NPA2) was grown at 30°C in YPGal+Suc (C) or shifted to YPD for 6 h (D), 12 h (E), and 24 h (F). Cells were harvested at an OD₆₀₀ of 0.8, and cell extracts were resolved in 7% to 50% polysome sucrose gradients. The A₂₅₄ was continuously measured. Sedimentation is shown from left to right. The peaks of free 40S and 60S r-subunits, 80S free couples-monosomes, and polysomes are indicated. Half-mers are labeled by arrows.