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. Author manuscript; available in PMC: 2013 Dec 15.
Published in final edited form as: Science. 2012 Dec 20;339(6121):10.1126/science.1232458. doi: 10.1126/science.1232458

Figure 5. cGAS is a DNA binding protein.

Figure 5

(A) Indicated GST fusion proteins were expressed and purified from E. coli and then incubated with Streptavidin beads in the presence of ISD or biotin-ISD. Bound proteins were eluted with SDS sample buffer and detected by immunoblotting with a GST antibody. (B) Flag-h-cGAS was expressed and purified from HEK293T cells and then incubated with streptavidin beads as described in (A) except that a Flag antibody was used in immunoblotting and a biotin-RNA was also tested for binding to cGAS. (C) Flag-tagged full-length or truncated human cGAS proteins were expressed in HEK293T cells and affinity purified. Their ability to bind biotin-ISD was assayed as described in (B). Right panel: Expression plasmids encoding full-length and deletion mutants of h-cGAS were transfected into HEK293T-STING cells followed by measurement of IFNβ RNA by q-RT-PCR.