SUMOylation of RNA-binding proteins (Li et al. 2004, reviewed in Filosa et al. 2013) alters their interactions with nucleic acids and with proteins. Whereas SUMOylation of HNRNPC decreases its affinity for nucleic acid (ssDNA), SUMOylation of NOP58 is required for binding of snoRNAs. SUMOylation of HNRNPK is required for its coactivation of TP53-dependent transcription.