Primer Extension Assay is a simple method of assessing expression levels. The total RNA produced by the culture is isolated. A short synthetic oligonucleotide primer (complementary to a short sequence on the target RNA) is radiolabelled (usually with 32P) and the primer anneals to the RNA. Reverse transcriptase then extends the RNA producing cDNA. The cDNA is analyzed on a polyacrylamide gel. The amount of cDNA in a band on the gel is proportional to the amount of initial RNA, thus providing expression levels of RNA from the culture.
Regulated genes for each binding site are displayed below. Gene regulation diagrams
show binding sites,
both positively and negatively regulated
genes, genes with unspecified type of regulation.
For each indvidual site, experimental techniques used to determine the site are also given.