[1] In mammalian cells, cGAMP is synthesized by cyclic GMP-AMP synthase (cGAS) from ATP and GTP upon cytosolic DNA stimulation.

[3][4][5][6] This molecule, referred to as 2′3′-cGAMP (cyclic [G(2’,5’)pA(3’,5’)p]), functions as an endogenous second messenger inducing STING-dependent type I interferon response.

[1][3] cGAMP has also been shown to be an effective adjuvant that boosts the production of antigen-specific antibodies and T cell responses in mice.

[8] [9] In recent years, cGAMP signalling has been identified in prokaryotes including Vibrio cholerae which express a bacterial analogue of cGAS.

In these organisms, cGAS is encoded as part of an operon alongside cGAMP-activated phospholipases (e.g. CapV in V. cholerae).