The protein encoded by this gene is a DNA binding cytosolic protein that catalyzes the synthesis of cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) after sensing the presence of DNA in the cytoplasm. cGAMP binds another protein, Stimulator of interferon genes (STING), leading to the induction of interferons, and a host immune response. Reduced expression of this gene inhibits interferon induction in the presence of some viral infections. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2014],E330016A19Rik, cGAS,CGAS