Ubiquitylation and SUMOylation regulate transcription in several ways: 1) Ubiquitylation of histones H2A and H2B is associated with actively transcribed genes and marks transcriptionally active chromatin. 2) The enzyme Rad6 ubiquitylates histone H2B, promoting methylation of histone H3 and telomeric gene silencing. 3) SUMOylation differs from ubiquitylation in that it does not target proteins for degradation, but rather stabilizes or targets proteins to subnuclear structures.