Promega, E1980, Dual-Luciferase® Reporter Assay System

Why Use a Dual-Luciferase System Instead of a Single Reporter?
A single luciferase reporter assay measures absolute luminescence from only the experimental construct. While convenient, single-reporter data are sensitive to well-to-well differences in transfection efficiency, cell viability, and lysis completeness—sources of variability that have nothing to do with the biology being studied. The DLR™ Assay addresses this limitation directly. By cotransfecting a second luciferase reporter under a weak constitutive promoter (e.g., pRL-TK [ Cat.# E6921 ] expressing Renilla luciferase), every sample carries its own internal standard. Normalizing firefly to Renilla reduces technical noise without requiring the user to split samples, run parallel lysates or add separate protein quantification steps. For more information, see Designing a Bioluminescent Reporter Assay: Normalization Options . Additional advantages of the dual-reporter format:
No sample splitting: both reporters are measured from the same lysate tube or well.
Detects weak promoters: the 7-log linear range and attomole sensitivity when used with a sensitive luminometer make detecting a change in signal possible even when expression is very low.
No endogenous interference: mammalian cells have no intrinsic luminescence activity, so assay background is negligible.
Both reactions complete in ~4 seconds per sample with auto-injector luminometers, supporting high-throughput workflows.