What are reporter genes and how are they used in research?

Reporter genes encode easily detectable proteins used to study gene expression and regulation. Common reporters include: GFP (green fluorescent protein) for live-cell imaging, luciferase for sensitive bioluminescence assays, beta-galactosidase (lacZ) for colorimetric assays, and CAT (chloramphenicol acetyltransferase). Reporters are placed under control of promoters of interest to measure transcriptional activity, screen for regulatory elements, track protein localization, or assess transfection efficiency. Fusion proteins with reporters enable protein tracking. Reporter assays are fundamental tools in molecular biology, drug screening, and gene therapy development.