A 1.0-kb DNA fragment from the 5' end of the mouse gene is examined by DNA footprint protection analysis. Two samples are end-la
beled with 32P, and one of the two is mixed with TFIIB, TFIID, and RNA polymerase II. Both samples are exposed to DNase I. The results are displayed below. The DNA exposed to proteins is run in the right-hand lane of the gel. Control DNA is in the left-hand lane. Required:
What length of DNA is bound by the transcriptional proteins?
Proteins, such as RNA (ribonucleic acid) polymerase, were loaded into lane 2. TFIIB and TFIID are two forms of TFII. These proteins attach to the fragment of DNA. Furthermore, these proteins shield DNA from the DNase enzyme, which may trigger DNA to split. As a result of the above findings, we may conclude that the inserting proteins(RNA polymerase, TFIID and TR 8 proteins) cover the area between 500 and 800 bp (base pair) in the DNase I footprinting experiment.
As a consequence, the length duration is 300bp since the promoter area is about 500-800bp and is not digested by DNase after incubation of inserting proteins.
