FIG. 1.

Phosphorylation of RIG-I CARDs. (A) RIG-I 2CARD phosphorylation sites determined by MS. (Left) Coomassie-stained purified GST-RIG-I 2CARD (amino acids 1 to 200). (Right) RIG-I structure and amino acid sequence of the N-terminal CARDs. Arrows indicate the ubiquitinated forms of GST-RIG-I 2CARD. Phosphorylation sites identified by MS are highlighted in red. The blue lysine residues indicate the sites of ubiquitination (10). The area around Thr-170 is highlighted in yellow. N.S., nonspecific band. (B) MS/MS spectra of tryptic phosphopeptides pSLQAFQDYIR, SDKENWPKpTLK, and GIKDVEpTEDL, which identified phosphorylation sites at Ser-8, Thr-170, and Thr-197. p, phosphorylation. b- and y-ion designations are shown (2).