Invivogen 2'3'-CGAMP
2’3’-cGAMP (cyclic [G(2’,5’)pA(3’,5’)p]) is produced in mammalian cells by cGAS (cGAMP synthase) in response to double-stranded DNA in the cytoplasm. 2’3’-cGAMP is also referred to as “noncanonical“ cGAMP due to the presence of the atypical 2’-5’ phosphodiester linkage between the guanosine and the adenosine. Similar to the canonical 3’3’-cGAMP, 2’3’-cGAMP serves as a second messenger to activate innate immune responses by binding to STING (stimulator of IFN genes) and subsequently inducing the TBK1-IRF3-dependent production of IFN-β [1]. Structural and functional studies revealed that noncanonical 2’3’-cGAMP is distinct from the canonical 3’3’-cGAMP produced by bacteria [2,3]. 2'3'-cGAMP binds to STING with a much greater affinity than 3'3'-cGAMP [1]. Certain variants of STING are able to distinguish between noncanonical and canonical cGAMP [2]