Gal4-UAS System in Drosophila

The Gal4-UAS system drives gene expression in many cell- and tissue-specific modes in fruit flies. It has been expanded and has become the basis of many modern tools for manipulating gene expression in Drosophila and other model organisms. The system contains two parts usually distributed in two transgenes respectively. One is the Gal4 and the other is the UAS (upstream activating sequence)-gene expression components. The basic Gal4 protein contains 881 amino acids as a transcription activator, which can specifically recognize and bind to UAS DNA sequence to drive UAS downstream gene expression. As multiple lines are generated, a panoply of modified Gal4-UAS systems have been created for expressing genes of interest, large-scale knock-down or knock-out genes, high-throughput screening, and analysis of genome-wide protein-DNA interactions.

CD BioSciences offers specialized end-to-end Gal4-UAS system strategy services in model organism – Drosophila. Relying on our comprehensive Gal4 lines and enhancers stock and advanced transgenic platform, customers can quickly mate UAS-target genes line with a variety of Gal4 lines supporting research needs. Besides, we are experts at refining Gal4-UAS system and fusing them into any site-specific flies' genome enabling customized gene function and interaction researches.

What is GAL4-UAS system?

In basic Gal4-UAS system, Gal4 driver directs the expression of Gal4 protein for precise control. Interested genes like reporter gene can be embedded into UAS sequence, which includes multiple GAL4 protein binding sites. Once Gal4 combines UAS, the expression of a gene carried downstream of UAS is initiated transcription. The Gal4 driver and UAS-target gene fly lines are generated and maintained as separate stocks. In the absence of GAL4, the target gene is not expressed. Crossing a fly expressing GAL4 to a fly carrying UAS-target genes results in targeted gene expression in the progeny of the cross. The great advantage of such a two-position system is that it is only necessary to cross different GAL4 lines with the same UAS transgenic Drosophila, so as to achieve high throughput expression and save effort to construct and screen the dislocation of expression or expression in specific organs transformants.

Basic Gal4-UAS System in Drosophila Fig.1 Basic Gal4-UAS System in Drosophila

Our GAL4-UAS System Service Includes

  • Gal4 Gal80 System
  • Gal4 Gal80 system uses Gal80 transgenes, which binds to Gal4 and blocks transcriptional activation, refines the precise expression pattern of Gal4-dependent transgenes.

  • GeneSwitch Gal4 System
  • The GeneSwitch Gal4 is a modified Gal4-UAS system, whereby transgene expression is induced slowly in Drosophila by adding the drug RU486 (mifepristone) to food.

  • Split Gal4 System
  • Split Gal4 system remains only 2 parts of Gal4 primary domains driven by different enhancers, the DNA binding domain and transcriptional activation domain. The transcription of target-gene activated when the 2 Split Gal4 hemi-drivers combined correctly.

  • Gal4 RNAi
  • In Drosophila, RNAi is achieved by expressing artificial inverted repeat (IR) sequences complementary to related genes. Gal4 inducible RNAi system is attained when UAS is put in front of the IRs.


  • Genes/proteins function study at all stages of development.
  • in vivo visualization of subcellular structure.
  • High-throughput mutants and screening
  • Transmission in neuronal subclasses study
  • Signaling pathway study and cell communication
  • Partial rescue of mutant phenotypes

Why CD BioSciences?

  • Record-proven expertise and experience in Gal4-UAS system and Drosophila.
  • Consistent results and Superior efficiency.
  • Fast turnaround services.
  • Best after-sale service in vector construction and library screening.

With years of expertise, CD BioSciences project management team provides high-quality and powerful Drosophila Gal4-UAS construction and modification strategy enabling clients to study gene function, tissue mapping, disease and development mechanisms, high-throughput screening, and treatment strategy, etc. Please feel free to contact us starting your private project customization.


  1. Caygill EE, et al. (2016). The GAL4 system: a versatile system for the manipulation and analysis of gene expression. Methods Mol Biol. 1478 (2016), pp. 33-52.

For research use only. Not intended for any clinical use.

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