Dissociation of vacant 80S ribosomes by Pelota, Hbs1 and ABCE1. (A–D) Dissociation of vacant 80S ribosomes containing [32P]60S subunits by incubation with Pelota, Hbs1 and ABCE1 (A, B) in the presence of (A) different concentrations of Pelota and (B) different nucleotides at 1.5 mM free Mg2+, (C) at different free Mg2+ concentrations and (D) after different incubation periods at 1.5 mM free Mg2+, assayed by SDG centrifugation. Upper fractions were omitted for clarity.