(A) Imp4p prefers low salt for binding. 32P-labelled TG30 (5 nM) was incubated with 1 μM Imp4p and 0.05, 0.1, 0.2, 0.4 or 0.8 M NaCl at room temperature for 10 min. Unlabelled TG30 (1 μM) was added to the reaction mixtures and a gel-shift assay was then performed. The binding was quantified using a PhosphorImager, and the activity with 0.05 M NaCl was taken as 100%. (B) Slow dissociation of Imp4p from single-stranded TG1–3 DNA. 32P-labelled TG30 (15 nM) was incubated with 1 μM Imp4p at room temperature for 10 min. Unlabelled TG30 (1 μM) was then added at zero time. Aliquots of the mixtures were withdrawn at the indicated time points and were loaded on to a running gel. After electrophoresis, the amount of 32P-labelled TG30 remaining bound was quantified using a PhosphorImager and the binding at zero time was taken as 100%.