As with motif discovery, TF-binding sites search benefits from a comparative genomics approach. Searching a single genome for TFBS will yield very noisy results. If a number of related genomes are searched, then the search results can be compared and strengthened by requiring that a site be located, for instance, in the promoter region of the same gene for at least two or three species. As in the case of motif discovery, these methods are not often applied to verify experimental results, but can be used to guide experimental research. For instance, comparative genomics searches can be implemented to detect good candidate sites, which are then verified using an experimental technique.

In DNA affinity purification, DNA from promoter regions thought to be bound by the protein is labelled (e.g. biotinylated) and bound to beads (or some type of matrix). The protein is then left to interact with DNA and eventually eluted. Bound protein will remain attached to beads. This can be detected through gel electophoresis. The protein can then be sequenced by mass-spectrometry. The techinque can be used to demonstrate binding of a purified protein, or to purify the binding protein from crude extract or a mix of proteins.

DNA-arrays (or DNA-chips or microarrays) are flat slabs of glass, silicon or plastic onto which thousands of multiple short single-stranded (ss) DNA sequences (corresponding to small regions of a genome) have been attached. After performing a mRNA extraction in induced and non-induced cells, the mRNA is again reverse transcribed, but here the reaction is tweaked, so that the emerging cDNA contains nucleotides marked with different fluorophores for controls and experiment. Targets will hybridize by base-pairing with those probes that resemble them the most. The array can then be stimulated by a laser and scanned for fluorescence at two different wavelengths (control and induced). The ratio or log-ratio between the two fluorescence intensities corresponds to the induction level.

The DNAse foot-printing method starts by focusing on a given region of interest (e.g. a promoter region) and amplifying it by PCR to obtain lots of sample. It then throws in the TF and then the DNAse. The mix is left to stir for a short time and then gel electrophoresis is run to compare the pattern of fragments in a control (no TF) and in the sample. If the TF has bound the sample, it will have protected a stretch of DNA (encompassing some fragments of the control) and thus those fragments will not appear in the sample gel. The fragments can then be cut-out from the gel, purified and sequenced to obtain the sequence of the protected region. This is often used to identify the binding motif of a TF for the first time. The foot-printing will typically resolve the protected region down to 50-100 bp, and the sequence can be then examined for possible TF-binding sites either by eye of using a computer search.

MSA can be used to align promoter regions and highlight regions of conservation that may be indicative of transcription factor binding sites.

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.

Target-specific mutation, as opposed to non-specific mutation. In the context of TF-binding sites, site-directed mutagenesis is typically used to establish/confirm the specific sequence and location of a site, often in tandem with EMSA. Different positions of a putative binding site are mutated to non-consensus (or random) bases and binding to the mutated site is evaluated through EMSA or other means. Often implemented only in conserved motif positions or serially through all positions of a site.