Analysis of mortalin mutants for PP1α or MEK2 interaction. (A) Schematic of the mortalin mutants used in this study. AD, ATPase domain; SD2, subdomain 2; PBD, peptide-binding domain; V482F, Val482Phe; V487A/Y, Val487Ala or Val487Tyr; Δtail, tail deletion. (B) Total lysates of SK-MEL 28 cells infected with lentiviral pHAGE expressing N-terminally HA-tagged mortalin mutants for 2 days were analyzed by immunoblotting for co-IP of indicated proteins. (C) In vitro binding assay using 0.5 μM recombinant GST-PBD mutants and HIS-PP1α. (D) In vitro binding assay using 0.5 μM recombinant GST-PBD mutants and HIS-MEK2. (E) Schematic of the peptide aptamers (APT) designed from the groove region of PBD. (F) SK-MEL 28 cells infected with pHAGE expressing N-terminally HA-tagged PBD mutants were treated with 4 μM synthetic peptide aptamers for 2 days. Equal volumes of dimethylformamide were added to untreated cells. Total cell lysates were analyzed by immunoblotting for co-IP of the indicated proteins.