Protein disulfide-isomerase interacts with soluble guanylyl cyclase via a redox-based mechanism and modulates its activity

Biochem J. 2013 May 15;452(1):161-9. doi: 10.1042/BJ20130298.


NO binds to the receptor sGC (soluble guanylyl cyclase), stimulating cGMP production. The NO-sGC-cGMP pathway is a key component in the cardiovascular system. Discrepancies in sGC activation and deactivation in vitro compared with in vivo have led to a search for endogenous factors that regulate sGC or assist in cellular localization. In our previous work, which identified Hsp (heat-shock protein) 70 as a modulator of sGC, we determined that PDI (protein disulfide-isomerase) bound to an sGC-affinity matrix. In the present study, we establish and characterize this interaction. Incubation of purified PDI with semi-purified sGC, both reduced and oxidized, resulted in different migration patterns on non-reducing Western blots indicating a redox component to the interaction. In sGC-infected COS-7 cells, transfected FLAG-tagged PDI and PDI CXXS (redox active site 'trap mutant') pulled down sGC. This PDI-sGC complex was resolved by reductant, confirming a redox interaction. PDI inhibited NO-stimulated sGC activity in COS-7 lysates, however, a PDI redox-inactive mutant PDI SXXS did not. Together, these data unveil a novel mechanism of sGC redox modulation via thiol-disulfide exchange. Finally, in SMCs (smooth muscle cells), endogenous PDI and sGC co-localize by in situ proximity ligation assay, which suggests biological relevance. PDI-dependent redox regulation of sGC NO sensitivity may provide a secondary control over vascular homoeostasis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Chlorocebus aethiops
  • Enzyme Activation / physiology
  • Guanylate Cyclase / chemistry
  • Guanylate Cyclase / metabolism*
  • Humans
  • Mice
  • Oxidation-Reduction
  • Protein Binding / physiology
  • Protein Disulfide-Isomerases / chemistry
  • Protein Disulfide-Isomerases / metabolism*
  • Protein Interaction Mapping* / methods
  • Rats
  • Receptors, Cytoplasmic and Nuclear / chemistry
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Soluble Guanylyl Cyclase


  • Receptors, Cytoplasmic and Nuclear
  • Guanylate Cyclase
  • Soluble Guanylyl Cyclase
  • Protein Disulfide-Isomerases