Transcription Factors affect Target Genes
- Transcription Factors move from the cytoplasm to the nucleus
- In the nucleus they bind to specific DNA sites near the start of target genes.
- They control expression by controlling the rate of transcription
- Some transcription factors called activators, increase the rate of transcription e.g: they help RNA polymerase bind to the start of target gene and activates transcription (Proto-onco genes)
- Other transcription factors, called repressors, decrease the rate of transcription by binding to the start of a gene preventing RNA polymerase from binding, and preventing transcription (Tumor suppressor genes)
Oestrogen's affect on Transcription of Target Gene
- Oestrogen is a hormone that can affect transcription by binding to a transcription factor called an oestrogen receptor, forming an oestrogen-oestrogen receptor complex.
- The complex moves from the cytoplasm into the nucleus where it binds to specific DNA sites near the start of the target gene.
- The complex can either act as an activator or a repressor. Whether it acts as a repressor or an activator depends on the type of cell and the target gene.
- Therefore, the levels of oestrogen in a particular cell, affects the rate of transcription of target genes.