Understanding "active" chromatin: a historical perspective of chromatin remodeling.

Two phenomena have long been observed to correlate with transcriptionally active chromatin: increased histone acetylation and increased sensitivity to nucleases, including specific patterns of nuclease hypersensitivity in the promoters of active or inducible genes. Work in recent years has at last identified protein complexes required to form these hallmarks of active chromatin: histone acetyltransferases (HATs) and ATP-dependent chromatin remodeling complexes. This review traces the history of these discoveries, including the development of essential tools that allowed the major advances in the field, and describes the current understanding of the interactions between HATs and ATP-dependent remodelers.