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Y-form DNA - cGAS agonist

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200 µg


cGAS activation with G3-YSD
cGAS activation with G3-YSD

cGAS Agonist

G3-YSD (G3-ended Y-form Short DNA) is a 26-mer DNA sequence derived from the HIV-1 RNA genome [1]. This short DNA displays a Y-shape arising from its palindromic sequence flanked by unpaired guanosine trimers (G3). The guanosine overhangs in this Y-form DNA have been identified as minimal recognition motifs for cGAS (cyclic GMP-AMP synthase, cGAMP synthase), a critical cytosolic DNA sensor [1].

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Mode of action:

cGAS detects double-stranded DNA (dsDNA) over 40 bp in length, or stem-loop structures of single-stranded DNA (ssDNA) flanked by unpaired nucleotides [1-3]. Interaction of cGAS with its agonists promotes the synthesis of 2’3’-cGAMP, a second messenger that activates STING (stimulator of interferon genes), and the downstream production of type I interferons (IFNs) and other cytokines [2]. Response to G3-YSD is strictly cGAS-dependent, as demonstrated by the lack of type I IFN production upon intracellular delivery of G3-YSD in cGAS-KO cells (see figures).


Key features of G3-YSD:

  • Potent cGAS-specific agonist
  • Y-form Short DNA flanked with guanosine trimers
  • Each lot is functionally tested


Read our review on cGAS.



1. Herzner A.M. et al., 2015. Sequence-specific activation of the DNA sensor cGAS by Y-form DNA structures as found in primary HIV-1 cDNA. Nat Immunol. 16(10):1025-33.
2. Li T. & Chen Z.J., 2018. The cGAS-cGAMP-STING pathway connects DNA damage to inflammation, senescence, and cancer. J Exp Med.215(5):1287-1299.
3. Luecke S. et al., 2017. cGAS is activated by DNA in a length-dependent manner. EMBO Rep. 18(10):1707-1715.


Evaluation of IRF induction
Evaluation of IRF induction

Intracellular delivery of G3-YSD induces a potent IRF response in a dose-dependent manner. THP1-Dual™ cells were stimulated with increasing concentrations of G3-YSD, G3-YSD Control or VACV-70 complexed with LyoVec™, or 1 x 104 U/ml hIFN-β. After overnight incubation, the IRF response was assessed by determining Lucia luciferase activity in the supernatant using QUANTI-Luc™ 4 Lucia/Gaussia. For each ligand, the response is expressed relative to that of hIFN-β (taken as 100%). 

Evaluation of signaling pathway
Evaluation of signaling pathway

IRF response upon intracellular delivery of G3-YSD is strictly dependent on cGAS. THP1-Dual™ and THP1-Dual™ KO-cGAS cells were stimulated with 1 μg/ml G3-YSD, G3-YSD Control or VACV-70 complexed with LyoVec™, or 1 x 104 U/ml hIFN-β. After overnight incubation, the IRF response was assessed using QUANTI-Luc™ 4 Lucia/Gaussia and expressed relative to that of hIFN-β (taken as 100%).

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Activity: cGAS agonist

Working concentration: 100 ng - 1 μg/ml


Note: G3-YSD contains a palindromic sequence for which self-hybridization results in double-stranded DNA. The flanking guanosine trimers in 5' and 3' remain unpaired.

Molecular weight: 8088.1 g/mol

Control: G3-YSD Control

Quality control: 

  • The biological activity has been verified using cellular assays.
  • The absence of bacterial contamination, such as lipoproteins and endotoxins, has been confirmed using HEK-Blue™ TLR2 and HEK-Blue™ TLR4 cells.
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  • 200 μg G3-YSD (G3-ended Y-form Short DNA)
  • 1.5 ml sterile endotoxin-free water

room temperature G3-YSD is shipped at room temperature.  

storeUpon receipt, store at -20°C.

stable Resuspended product is stable for 12 months at -20°C.

Alert Avoid repeated freeze-thaw cycles.

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Cyclic GMP-AMP synthase (cGAS, cGAMP synthase) is a critical cytosolic DNA sensor that triggers innate immune responses through the production of type I interferons (IFNs) [1]. In response to cytosolic double‑stranded DNA (dsDNA), cGAS produces the cyclic dinucleotide (CDN) 2’3’-cGAMP.
CDNs bind directly to STING, leading to TBK1‑IRF3-mediated activation of IFN-stimulated response elements (ISRE) in the promoters of IFN-stimulated genes (ISG). The most potent agonist of human STING is 2’3’-cGAMP [2,3].



1. Sun L. et al., 2013. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science 339(6121):786-91.
2. Gao P. et al., 2013. Cyclic [G(2’,5’)pA(3’,5’)p] is the metazoan second messenger produced by DNA-activated cyclic GMP-AMP synthase. Cell. 153(5):1094-107.
3. Ablasser A. et al., 2013. cGAS produces a 2’-5’-linked cyclic dinucleotide second messenger that activates STING. Nature. 498(7454):380-4.

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