TF paralogs-Natural experiments in DNA binding

Transcription factor (TF) paralogs provide unique insights into how DNA-binding specificity evolves and diversifies. While paralogous TFs share conserved, highly similar DNA-binding domains, they achieve distinct regulatory functions through mechanisms that are now being elucidated. This review examines how sequence variations between paralogs translate into functional diversity, including how mutations distant from the DNA interface can allosterically modulate binding specificity. We focus on competitive binding dynamics when paralogs are co-expressed and discuss emerging evidence that TFs recognize extensive repertoires of lower-affinity binding sites. Differential preferences for lower-affinity binding sites create paralog-specific binding patterns that determine TF genomic occupancy. These insights have important implications for interpreting the impact of coding and noncoding variation on TF-DNA interactions and human disease.