Formation of the transcriptional initiation complex: from general factors to chromatin remodeling complexes

The description of the gene transcription machinery is now possible at the molecular level. Despite the high level of complexity of RNA polymerase II, this enzyme requires additional components for accurate rate transcription . These general transcription factors, together with RNA polymerase II, ass emble on the promoter in order to form the pre-initiation complex, and allo w for basal transcription. Gene expression is then regulated through the bi nding of proteins to specific sequences. The activators then bind other pro teins in cooperation with intermediary factors, and convey signals to the b asal transcription machinery. This complicated mechanism of gene expression is further complicated by the machinery responsible for modulating the chr omatin structure, which includes histones acelylation and chromatin remodel ing.