Gene promoter

A region of DNA that initiates transcription of a particular gene

A gene promoter is a region of DNA that initiates transcription of a particular gene. Promoters are located near the transcription start sites of genes, on the same strand and upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long.

Structure

Promoters are composed of specific sequences that provide a binding site for RNA polymerase and other transcription factors. The core promoter is the minimal portion of the promoter required to properly initiate transcription. It typically includes the TATA box, a conserved sequence found in many promoters, and the transcription start site (TSS).

Core Promoter Elements

• TATA Box: A DNA sequence found about 25-35 base pairs upstream of the transcription start site. It is recognized by the TATA-binding protein (TBP), a subunit of the transcription factor TFIID.
• Initiator (Inr): A core promoter element that overlaps the transcription start site.
• Downstream Promoter Element (DPE): Located downstream of the transcription start site, it is recognized by TFIID in the absence of a TATA box.

Function

Promoters are essential for the regulation of gene expression. They determine the site of transcription initiation and influence the frequency of transcription initiation. Promoters can be regulated by various factors, including:

• Transcription Factors: Proteins that bind to specific DNA sequences within the promoter to regulate transcription.
• Enhancers: DNA sequences that can increase the transcription of a gene from a distance.
• Silencers: DNA sequences that can repress transcription.

Types of Promoters

Promoters can be classified based on their function and the type of genes they regulate:

• Housekeeping Promoters: These promoters regulate genes that are expressed in all cell types and are essential for basic cellular functions.
• Tissue-Specific Promoters: These promoters regulate genes that are expressed in specific tissues or cell types.
• Inducible Promoters: These promoters are activated in response to specific stimuli or environmental conditions.

Research and Applications

Understanding promoters is crucial for genetic engineering and gene therapy. By manipulating promoter sequences, scientists can control the expression of genes in transgenic organisms or in therapeutic contexts.

Also see

• Transcription (genetics)
• RNA polymerase
• Transcription factor
• Gene expression
• Enhancer (genetics)