Transcription factors have a modular structure, allowing the combination of different domains through alternative splicing to provide greater specificity to DNA binding and response. This was discovered through deletion analysis, allowing the identification of individual ‘modules’, or domains.
This modular structure is significant, as it is possible to study this in a yeast two-hybrid assay. By separating the DNA-binding domain and the activation domain to bait and prey proteins, it can be determined whether there are protein-protein interactions occurring between them. By using a reporter gene, it is possible to assay the transcriptional activity that occurs on successful binding between the bait and the prey (or the lack thereof if no interaction occurs).