Figure 3.

Conjugation of different Arabidopsis SUMO isoforms to ScPCNA. ScPCNA labeled with a Myc tag was purified from E. coli and directly applied to the gel (control in lane 1), or incubated with the Arabidopsis E1 and E2 enzymes and either Arabidopsis ubiquitin (lane 2), the ubiquitin variant K48/R (lane 3), AtSUMO1 (lane 4), AtSUMO2 (lane 5), or AtSUMO3 (lane 6). Proteins were separated on a 12% SDS-polyacrylamide gel, and ScPCNA mobility shifts were detected by western-blot analysis using a Myc peptide-specific antiserum. SUMOylated ScPCNA species are marked by a bracket, and a signal of unclear origin is labeled with an asterisk (*).