2'2'-cGAMP is a synthetic dinucleotide (CDN) that contains non-canonical 2'5'-phosphodiester bonds. It binds to the adapter protein stimulator of interferon genes , which is a component of the innate immune response that activates the type I interferon pathway when bound to cyclic dinucleotides. 2'2-cGAMP shows weaker binding to STING than 2'3'-cGAMP but binds more strongly than 3'3'-cGAMP , cyclic di-GMP , or 3'2'-cGAMP, which bind in the micromolar range (Kds = 1.04, 1.21, or 1.61 μM, respectively). Despite weaker binding, 2'2'-cGAMP induces IFN-β production in the same concentration range as 2'3'-cGAMP (EC50s = 15.8 and 19.4 nM, respectively, in L929 cells).