In a GST pull-down assay, a gene of interest is fused with the GST gene, which codes for Glutathione S-transferase. Glutathione S-transferase has a high affinity for glutathione; consequently, the hybrid protein can be pulled down (purified) from cells using membranes coated with glutathione. If the gene of interest is bound to DNA, this DNA will be also pulled down and can be then analyzed by qPCR or sequencing.

Quantitative PCR (or quantitative real time polymerase chain reaction) is a modification of the conventional PCR reaction used to amplify and simultaneously quantify a targeted DNA molecule. In its more standard incarnation, a inactive fluorescent dye is added to the PCR mix. This dye is activated upon binding double-stranded DNA; as the PCR iterates, there is more and more dsDNA and therefore more fluorescence intensity.