S -Nitrosylation of actin by NO donors. A. Time courses of S-nitrosylation of actin in PC12 cells by NO donors. PC12 cells (7 × 105 cells/dish) cultured in 6-cm dishes were exposed to 300 μM NOR1 or NOR3 for the indicated times. The cell lysates in HEN buffer were subjected to the biotin-switch assay as described in "Methods." Samples were resolved by non-reducing SDS-PAGE and immunoblotted with anti-biotin and anti-actin antibodies for S-nitrosylated and total actin, respectively. Intensity of bands was quantified by using ImageJ. The extent of S-nitrosylated actin was normalized to total actin, and the ratio (mean ± SEM, n = 6) of S-nitrosylated actin to total actin at 0 min was taken as "1." *P < 0.05; **P < 0.01 vs. 0 min for NOR1; # P < 0.05 vs. 0 min for NOR3. B. Time courses of S-nitrosylation of actin by NO donors. Purified actin (5 μg) was incubated with 100 μM NO donor NOR1 or NOR3 for the indicated times and subjected to the biotin-switch assay. *P < 0.05; **P < 0.01 vs. 0 min for NOR1.