Question

What sequence elements are found within the core promoter of protein-encoding genes in eukaryotes? Describe their locations and specific functions.

Short answer

The core promoter of a protein-encoding gene in eukaryotes usually contains the following elements: TATA box, Inr, DPE, and sometimes BRE. The TATA box is located about 25-30 base pairs upstream of the transcription start site (TSS) and binds the TBP of the TFIID complex, setting the direction of transcription. The Inr and DPE sequences help position RNAP II for transcription, while BRE interacts with TFIIB for precise transcription initiation.

Step-by-step solution

Identify Core Promoter

The core promoter is the region in a DNA sequence where RNA Polymerase II (RNAP II) binds and initiates transcription. This region is usually located upstream of the transcription start site (TSS).

Detail Core Promoter Elements: TATA Box

The TATA box, a highly conserved DNA sequence (TATAAAA), is an essential part of the core promoter and is located about 25-30 base pairs upstream of the TSS. The TATA box is recognized and bound by a protein factor named TATA-binding protein (TBP), which is a subunit of the TFIID complex; this binding determines the direction of transcription and sets the stage for efficient transcription initiation.

Detail Core Promoter Elements: Inr and DPE

Two other important elements in a core promoter are Inr (Initiator) and DPE (Downstream Promoter Element). The Inr sequence overlaps with the TSS and is recognized by the TFIID complex, guiding RNAP II to the correct start site for transcription. DPE, located approximately 30 base pairs downstream of the TSS, is also recognized by TFIID and helps to position RNAP II correctly for transcription.

Detail Core Promoter Element: BRE

BRE (TFIIB recognition element) is another important element found in some eukaryotic core promoters. This sequence lies just upstream of the TATA box and interacts with TFIIB, another transcription factor crucial for accurate transcription initiation.

Summarize Function of Core Promoter Elements

In summary, the core promoter of a gene contains specific sequence elements that are recognized and bound by various transcription factors. These interactions determine the exact location where RNAP II binds to the DNA and initiates the transcription process. Knowing these sequences helps in understanding how gene expression is regulated in eukaryotes.