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. Author manuscript; available in PMC: 2021 Mar 10.
Published in final edited form as: Nature. 2020 Sep 10;587(7835):673–677. doi: 10.1038/s41586-020-2749-z

Figure 1. Tight nucleosome binding inactivates cGAS.

Figure 1.

a. Western blot analyses of cGAS expression in 1% SDS whole cell lysates (WCL), 0.2% NP-40 cytosolic fractions, 0.5 M NaCl nuclear extracts, and 1% SDS nuclear lysates of HeLa and cGAS−/− MEF SV40I + mcGAS-HA cells.

b. Immunofluorescence microscopy images of HeLa and cGAS−/− MEF SV40I + mcGAS-HA cells stained with anti-cGAS or –HA, and -α-tubulin antibodies and DAPI. The scale bars denote 50 μm.

c. The percentage of nuclear- to whole cell-cGAS ratio quantified by microscopy. All data are presented as mean ± SEM.

d. Surface plasmon resonance (SPR) shows that full-length human cGAS binds to in vitro reconstituted human nucleosome with nanomolar affinity. The binding affinity (Kd) was determined by fitting the binding data to a simple one-to-one binding model.

e. Enzyme activity assays by ion exchange chromatography show that nucleosome binding potently inhibits the catalytic activity of cGAS.