A 3.5-kb segment of DNA containing the complete sequence of a mouse gene is available. The DNA segment contains the promoter sequence and extends beyond the polyadenylation site of the gene. The DNA is studied by band shift assay (see Research Technique 8.1), and the following gel bands are observed. Match these conditions to a specific lane of the gel. 3.5-kb fragment alone

Key Concepts

Promoter Sequence

The promoter sequence is a region of DNA located upstream of a gene that initiates transcription. It contains specific binding sites for RNA polymerase and transcription factors, which are essential for the regulation of gene expression. Understanding the promoter's role is crucial for interpreting how the gene is activated and how it interacts with other regulatory elements.

Polyadenylation Site

The polyadenylation site is a sequence in the mRNA that signals the addition of a poly(A) tail, which is important for mRNA stability, export from the nucleus, and translation efficiency. In the context of the DNA segment, knowing where the polyadenylation site is located helps in understanding the full length of the mRNA produced and the functional aspects of the gene being studied.

Band Shift Assay

A band shift assay, also known as an electrophoretic mobility shift assay (EMSA), is a technique used to study protein-DNA interactions. In this assay, DNA fragments bound to proteins migrate more slowly through a gel than unbound DNA, resulting in distinct bands. This method is essential for analyzing how transcription factors interact with the promoter region of the gene, providing insights into gene regulation.