A Safety Considerations Many techniques discussed involve hazards, including high electrical current and voltage, radioactivity, and toxic chemicals. It is crucial to follow equipment manufacturers' instructions and adhere to local and federal safety regulations. B Introduction Gene expression in prokaryotes and eukaryotes is primarily regulated at the mRNA synthesis level. Advances in DNA sequencing methods have identified cis-acting regulatory elements like promoters and enhancers. Recent findings confirm that specific sequences within these elements serve as binding sites for sequence-specific proteins, particularly through "footprinting" assays (e.g., Galas and Schmitz, 1978). These assays have facilitated the recognition, isolation, and analysis of DNA-binding proteins for various genes. Comprehensive reviews on the structural studies of transcription regulatory proteins and related DNA elements are available (e.g., Glover, 1989; Johnson and McKnight, 1989) for readers seeking detailed insights. This volume provides a brief overview of previous studies to contextualize the applications of the techniques described herein. Protein-DNA interactions rely on specific tertiary configurations of the binding protein, enabling close contact with the DNA helix.
