25 - Transcription Factors

Abstract

Publisher Summary Initiation of transcription requires a variety of proteins that can be divided into the basal transcription machinery, consisting of RNA polymerase II (RNA pol II) and associated factors—often referred to as “general transcription factors”—and an array of specific transcription factors or activators that are responsible for conferring both gene and stimulus specificity to the transcriptional response. The general transcription factors are involved in the recognition of core promoter elements and stabilization of RNA pol II at the transcription start site. RNA pol II, along with the general transcription factors, can only direct basal transcription, and additional factors are required for regulated or inducible transcription. Regulated transcription results from the interaction between cis-acting regulatory DNA sequences in the promoters of target genes and sequence-specific trans-acting specific transcription factors. This may cause increased (transactivation) or decreased (transrepression) transcription of the associated gene. These regulatory elements are commonly found in the immediate 5′-region upstream of transcription start. However, more distal regions and elements within the gene itself may also be required for correct transcriptional control.