Extended Data Fig. 5. Effects of mutations in the C53-binding site on STING oligomerization in cells.

a and c, Representative images of cells expressing STING wild type or the mutants in the binding pocket and the TM3-TM4 loop, respectively. Hela cells were transfected with GFP-tagged human STING wild type or mutants. Cells were stimulated with cGAMP, C53 or both. Localization of STING-GFP in cells was monitored by the fluorescence signal of GFP. Nuclei were stained with DAPI. The experiments were repeated three times. The images are representatives from these experiments. As expected, STING showed a diffuse pattern in cells in the absence of an agonist. Both C53 and cGAMP induced puncta formation of STING wild type. C53-induced puncta formation was reduced or abolished by the mutations. b and d, Quantification of STING puncta formation in cells expressing the wild type or mutants. The bar graph shows the individual data points, mean and s.e.m. of the percentage of cells with STING forming large puncta from the three biological repeats. Statistical significance p-values between the wild type and mutants were calculated by two-tailed Welch’s t-test. Scale bar, 10 μm. Source data of puncta counting results are provided in the source data file.