Viral proteins are bona fide SUNO substrates.

<p>Plasmids encoding FLAG-tagged version of the indicated viral proteins were co-transfected in HEK293T cells together with a plasmid expressing His-tagged SUMO2. Total cells lysates were probed with an anti-FLAG antibody (left panel). Cell pellets were lysed in denaturing buffer containing 7M urea and SUMOylated proteins were affinity purified with Ni-NTA agarose beads. Western blots were probed with the anti-FLAG antibody (right panel). High molecular weight species corresponding to poly-SUMOylated proteins were detected by the FLAG antibody. One representative experiment out of three is shown.