Core promoter

Definition

The core promoter is the region of DNA located immediately upstream of the transcription start site where the transcription machinery assembles to initiate gene transcription. This area contains essential elements that are crucial for the binding of RNA polymerase and other transcription factors, facilitating the precise regulation of gene expression in eukaryotic cells.

5 Must Know Facts For Your Next Test

1. The core promoter is typically located within 100-200 base pairs upstream of the transcription start site and is crucial for initiating transcription.
2. Elements within the core promoter, such as the TATA box, help position RNA polymerase II at the correct start site for transcription.
3. While the core promoter is necessary for basal transcription levels, it can be modulated by other regulatory elements like enhancers and silencers.
4. The assembly of the pre-initiation complex at the core promoter involves various proteins, including general transcription factors that assist RNA polymerase II in starting transcription.
5. Variations in core promoter sequences can lead to differences in gene expression levels among different genes and cell types.

Review Questions

• How does the core promoter contribute to the regulation of gene expression in eukaryotes?
  • The core promoter is essential for the regulation of gene expression as it serves as the primary site for RNA polymerase binding and initiation of transcription. It contains critical elements like the TATA box that facilitate the assembly of the transcription machinery. Additionally, while it drives basal transcription levels, its activity can be influenced by nearby regulatory elements such as enhancers and silencers that enhance or repress transcription.
• In what ways do enhancers and silencers interact with the core promoter to influence gene transcription?
  • Enhancers and silencers interact with the core promoter through protein-DNA and protein-protein interactions. Enhancers bind specific transcription factors that can loop back to contact proteins at the core promoter, enhancing RNA polymerase's recruitment and activity. Conversely, silencers can recruit repressive factors that inhibit this process, effectively reducing transcription initiation. This interplay allows for precise control of gene expression in response to various cellular signals.
• Evaluate how mutations in core promoter regions might affect gene expression and what implications this could have for cellular function.
  • Mutations in core promoter regions can significantly disrupt gene expression by altering the binding affinity of transcription factors or RNA polymerase, leading to decreased or misregulated transcription. Such changes can have serious implications for cellular function, potentially resulting in diseases such as cancer where abnormal gene expression patterns contribute to uncontrolled cell growth. Understanding these mutations can help in identifying therapeutic targets and developing strategies for disease intervention.

Related terms

Transcription Factors: Proteins that bind to specific DNA sequences to regulate the transcription of genes, playing a key role in turning genes on or off.

TATA Box: A conserved DNA sequence found within the core promoter that serves as a binding site for transcription factors and RNA polymerase II.

Enhancers: Regulatory DNA sequences that can increase the likelihood of transcription by providing additional binding sites for transcription factors, even from a distance.