Reporter-based assays are biological assays used to measure the regulatory ability of an unknown DNA sequence, study gene regulation by cis- or trans-acting factors, or measure activation of cell signaling pathways.

 In these assays, the unknown promoter sequence is linked to an easily detectable reporter gene whose product can be easily detected and quantifiably measured. The expression levels of the reporter gene are monitored by quantitating the reporter protein enzymatic activity, which is used to characterize regulatory sequences, transcription factor activity, cell signaling, or signaling pathways. 

Common reporter genes include beta-galactosidase, luciferase, beta-lactamase, alkaline phosphatase, and GFP (green fluorescence protein).  

Luciferases are used to create bioluminescent reporter assays that are highly quantitative, sensitive across a broad dynamic range, and easily detected by measuring light output. 

Most reporter gene assays involve either one reporter gene or two, with the second reporter expressed from a "control" vector to normalize the results of the experimental reporter. 

The control reporter gene is typically driven by a constitutive promoter, and the control vector is cotransfected with the experimental reporter. 

The cells are exposed to different factors or conditions, the effect of which can be easily tracked by measuring changes in light emission. Various detection methods such as luminescence, absorbance, and fluorescence are used to measure expressed reporter gene protein. 

Reporter assays can also be used to quantitatively assess RNAi activity and identify modulators of RNAi. They can also be used to screen chemicals that disrupt androgen signaling.

The reporter cells use transient transfection to ensure reliable and accurate results, and the cells are optimized to provide the best experimental conditions with the reagents supplied in the kits, enabling easy standardization of experiments.
Reporter cell-based assay kits offer optimal assay sensitivity and dynamic range when quantifying receptor activity, making them a reliable and cost-effective screening service for pharmaceutical compounds, chemicals or environmental samples.