FIG. 1.

The RGG box is the major site of ICP7 arginine methylation. In vivo methylation assays were performed to determine the major site of ICP27 methylation. HeLa cells were infected with either wild-type HSV-1 KOS; ICP27 viral deletion mutant d1-2, d2-3, d3-4, d4-5 (ΔRGG), or d5-6; ICP27 truncation mutant n504; or ICP27 null mutant 27LacZ (14, 26, 36). Cells were incubated from 4.5 to 8 h after infection with medium containing either [³⁵S]methionine (A) or l-[methyl-³H]methionine (B), in the absence or presence of the translation inhibitor cycloheximide (CH). ICP27 was immunoprecipitated (IP), resolved by SDS-PAGE, and transferred to nitrocellulose. Total ICP27 protein was determined by Western blot analysis with the ICP27-specific monoclonal antibody H1119, and methylated ICP27 was determined by fluorography. (C) Densitometry was used to quantify the bands. The data shown were derived from a single experiment but are representative of several experiments. (D) The residues deleted in the mutants are shown.