Regulation of gene expression involves the recruitment to and assembly of multiprotein complexes on DNA. Métivier et al. used the promoter region of the pS2 gene to study how the human estrogen receptor stimulates transcription of this gene. Using chromatin immunoprecipitation (ChIP) analysis, they found more than 30 proteins that bind to the promoter in the presence of estrogen; however, many of these interactions were mutually exclusive. The complexes formed could be grouped into six different classes. Kinetic ChIP analysis revealed the order of complex assembly, and histone modifications were also monitored. Their analysis identified three types of cycles of ordered complex assembly and disassembly and chromatin modification, which they present in a model for the formation of one transcriptionally silent cycle followed by two distinct transcriptionally active cycles. — NG
Cell 115, 751 (2003).