New Insights into an Old Modification

Abstract
It has been well established that tagging proteins with ubiquitin targets them for degradation in the proteasome pathway. However, as Mizzen and Allis comment in their Perspective, now it turns out that the addition of ubiquitin to the H1 linker histone in chromatin contributes to the regulation of gene transcription. The TAF250 subunit of Drosophila TFIID has ubiquitinating activity. By adding ubiquitin to H1, it may act in concert with other modifying activities to enhance the accessibility of chromatin to transcription complexes, thus regulating which genes are transcribed.