FIG. 2.

Phosphorylation of HSV-1 gE. (A) HSV-1-infected cells were labeled with [³⁵S]methionine/cysteine or with [³²P]orthophosphate, and then glycoproteins gB, gC, gD, gE, and gI or thymidine kinase was immunoprecipitated. Proteins were subjected to electrophoresis and exposed to X-ray film. The positions of gE, pgE (the immature form of gE), and gI are indicated, as well as molecular mass markers. (B) The band corresponding to gE was excised, eluted from the gel, hydrolyzed with 5 N HCl, and combined with nonradioactive phosphoserine, phosphotyrosine, and phosphothreonine as markers. Phosphoamino acids were separated using cellulose thin-layer plates. The positions of unlabeled phosphoamino acids were identified by ninhydrin staining, and those of the radiolabeled amino acids were identified by autoradiography.