Use of Escherichiu coli (E. coli) lacZ (β-Galactosidase) as a Reporter Gene

Our understanding of the molecular mechanisms that govern gene expression has been facilitated by the ability to introduce recombinant DNA molecules into heterologous cellular systems both in vitro and in vivo. One approach to defining DNA sequences important in the regulation of gene expression is to place controlling elements (e.g., promoter/enhancer sequences) upstream of a DNA coding sequence, introduce these constructs into transgenic animals or cells in culture, and analyze the levels of gene product produced by the introduced construct. Ideally, such a reporter gene should encode a product that is stable, innocuous to the cell or organism in which it is being expressed, and should be readily detectable, even when present in small quantities.