2'3'-cGAMP (sodium salt)

2’,3’-cGAMP (sodium salt) is a second messenger generated by the enzyme cGAMP synthase (cGAS) in the cytoplasm of mammalian cells, in response to the presence of double-stranded DNA.  As a second messenger, 2’,3’-cGAMP sodium salt activates innate immune responses via binding of STING (stimulator of IFN genes) and initiates the TBK1-IRF3-dependent production of IFN-β. 

It is used to identify small compounds that bind to STING. It is also applicable in the research of type I interferon response to cytosolic DNA. The binding affinity of 2’,3’-cGAMP to STING is 3.79 nM (Kd value), which is stronger than other cyclic di-nucleotides, e.g. cyclic di-GMP, 3’2’-cGAMP, 3’3’-cGAMP and 2’2’-cGAMP (Kds = 1.21 μM, 1.61 μM, 1.04 μM and 287 nM, respectively). 

References: 

Zhang X. et al., 2013. Cyclic GMP-AMP containing mixed phosphdiester linkages is an endogenous high-affinity ligand for STING. Mol Cell.51(2):226-35. 

Samira Khiar et al., 2017. Identification of a small molecule that primes the type I interferon response to cytosolic DNA.  Sci Rep, 7 (1), 2561 

Zhong B. et al., 2008. The adaptor protein MITA links virus-sensing receptors to IRF3 transcription factor activation. Immunity. 29(4):538-50.