Fig. (1) PERK binds E1 and E2. (upper panel) Phosphorimages of GST-pulldown reactions detecting binding of ³⁵S-labelled in vitro translated E2, E1 and NS4B polypeptides with GST, GST fusion proteins with wild type PERK (WT) or K618R mutant PERK (KR). One-tenth of in vitro translated reactions were run as input controls. Arrows denote polypeptides of the correct sizes. (lower panel) Coomassie Blue staining of the same gels showing the corresponding amounts of proteins used in the pulldown reactions. Asterisks denote protein bands of the correct sizes.