Sharon Dent: The unfolding SAGA of chromatin-modifying proteins

Histone modifications come in many flavors—phosphorylation, methylation, acetylation, and ubiquitination—that interact with each other to regulate the folding state of chromatin, with profound effects on gene expression. For example, histone acetylation reduces the affinity of histone N termini for DNA, promoting chromatin relaxation and allowing transcription factors easy access to DNA. Such modifications are essential for regulating the changes to genome organization and gene expression that take place during organismal development and cellular differentiation.