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Redox Regulation Of Type-I Inositol Trisphosphate Receptors In Intact Mammalian Cells., Suresh K. Joseph, Michael P. Young, Kamil Alzayady, David I. Yule, Mehboob Ali, David M. Booth, György Hajnóczky

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

A sensitization of inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release is associated with oxidative stress in multiple cell types. These effects are thought to be mediated by alterations in the redox state of critical thiols in the IP3R, but this has not been directly demonstrated in intact cells. Here, we utilized a combination of gel-shift assays with MPEG-maleimides and LC-MS/MS to monitor the redox state of recombinant IP3R1 expressed in HEK293 cells. We found that under basal conditions, ∼5 of the 60 cysteines are oxidized in IP3R1. Cell treatment with 50 μm thimerosal altered gel shifts, indicating oxidation of ∼20 cysteines. …