EUKARYOTIC TRANSCRIPTION INITIATION FACTORS AND THEIR FUNCTIONS

In eukaryotic cells, transcription initiation is a complex process that involves the coordinated action of multiple transcription factors. These factors play crucial roles in regulating gene expression by facilitating the binding of RNA polymerase to the promoter region of genes. Here are some of the key eukaryotic transcription initiation factors along with their functions:

1. TATA-binding protein (TBP):

• TBP is a subunit of the general transcription factor TFIID.
• It binds to the TATA box within the core promoter region of genes, helping to position RNA polymerase II for transcription initiation.

2. Transcription factor IIB (TFIIB):

• TFIIB interacts with TBP and helps in the recruitment of RNA polymerase II to the promoter.
• It also plays a role in stabilizing the pre-initiation complex.

3. Transcription factor IIF (TFIIF):

• TFIIF is involved in stabilizing the binding of RNA polymerase II to the promoter region.
• It also helps in the recruitment of RNA polymerase II and aids in the formation of the pre-initiation complex.

4. Transcription factor IIE (TFIIE):

• TFIIE is essential for the phosphorylation of RNA polymerase II, which is necessary for transcription initiation.
• It also helps in unwinding DNA at the transcription start site.

5. Transcription factor IIH (TFIIH):

• TFIIH has helicase activity, which is important for unwinding DNA during transcription initiation.
• It also plays a role in phosphorylating the C-terminal domain of RNA polymerase II, allowing it to escape the promoter and begin transcription elongation.

6. Mediator complex:

• The mediator complex acts as a bridge between transcription factors, RNA polymerase II, and the general transcription machinery.
• It facilitates communication between activators or repressors bound to enhancer sequences and the basal transcription machinery at the core promoter.

These eukaryotic transcription initiation factors work together to ensure accurate and regulated gene expression by controlling the initiation of transcription. Their coordinated actions are essential for proper cellular function and development.