Fig. 6.
SNO-Trx1 transnitrosylation of Prx1. A, both SNO-Trx1 and GSNO directly transnitrosylated Prx1 in vitro. B, MS/MS spectrum of Prx1 169HEGVC*PAGWKPGSDTIKPDVQK190 (m/z 2,349.2). Cys173 (C*, biotinylated) was nitrosylated. C, SNO-Prx1 levels were higher in Trx1C32S/C35S-expressing cells, and the differences were amplified following H2O2 treatment. D and E, Western blots of Prx1 species after separation on non-reducing gels. Overexpression of Trx1C32S/C35S rendered Prx1 more resistant to H2O2-induced dimer to monomer conversion (D), which correlated with the reduction of Prx-SO3H levels (E). Prx1 expression was not affected by either Trx1C32S/C35S expression or H2O2 treatment. F, statistical evaluation of E. Comparisons were made for Prx1 dimer, monomer, and Prx-SO3H between Trx1C32S/C35S-overexpressing cells and control cells. Values are the mean ± S.E. for experiments performed in triplicate (*, p = 0.0007; †, p = 0.006; ‡, p = 0.0001; Student's t test). Full-size blots are shown in supplemental Fig. S9B. Vec, vector.