Practice question

Gene regulation often involves sequence-specific DNA-binding proteins such as transcription factors and repressors interacting with cis-regulatory elements. DNase I footprinting directly visualizes interaction by protecting DNA backbone from nuclease cleavage where protein bound, leaving gap in cleavage ladder that maps binding motif at nucleotide resolution. Northern blotting measures transcript size and abundance, 5 prime RACE clones untranslated ends, and S1 mapping quantifies protected fragments; all focus on RNA rather than protein-DNA contact. Therefore footprinting provides mechanistic insight into regulatory protein occupancy, essential for studying transcriptional control and enhancer function.