Figure 4.

Binding of ribosome-associated polypeptides to SecB is reversible. Column chromatography of a gradient fraction containing ribosome-bound polypeptides (m370) to which His₆SecB (0.7 μM) was added was carried out as described for Fig. 3, except that following the 0.8-ml wash, the column received in the following order: 0.1 ml of SecB (1 mg/ml in wash buffer), 1 ml of wash buffer, then 3 ml of elution buffer.