Fig. 7. p97 is inhibited by hemin and contributes to CFTR degradation. (A) Coomassie Blue-stained SDS gels of His-tagged wild type (WT) and dominant-negative mutant (QQ) p97 purified on a Ni-NTA column and run on glycerol gradients. (B) ATPase activity of purified wild-type p97, mutant p97 and 26S RRL proteasomes was determined in the presence and absence of 40 µM hemin as described in Materials and Methods. (C) CFTR degradation was carried out in the presence of indicated molar excess of dominant-negative p97 (QQ). Graph shows the fraction (mean ± s.e.m.) of newly synthesized CFTR that was converted into TCA-soluble peptide fragments.