FIG. 4.

Identification of ORF66-induced phosphorylation of IE62 peptides. (A) Representation of the region of IE62 containing ORF66-directed phosphorylation sites, with the amino acid sequence in single-letter code and the position of each serine or threonine residue indicated with the residue number above. (B) Radiograph showing SDS-PAGE-separated immunoprecipitates of ³²P-labeled IE62 peptides expressed in the absence (−) and presence (+) of a 1:1 ratio of functional ORF66 protein kinase. All peptides contain residues 414 to 735 of the IE62 peptide, but with specific serine/threonine transitions to alanine, as indicated above each pair of lanes. The arrowhead indicates the expected size of the phosphorylated IE62 peptides. Lane numbers are indicated at the bottom of the radiograph for reference in the text.