FIG. 6.

Mutational analysis of the role of residues 78, 79, and 80 on position 79 phosphorylation and G₂ cell cycle arrest. (A) Schematic diagram of different Vpr mutants at positions 78, 79, and 80. +, Vpr is phosphorylated; −, Vpr is not phosphorylated. Average ratios of G₁ to G₂/M are listed under the G₂ arrest column. The data are from an average of two individual constructs of the same mutants. (B) Both ³²P- and ³⁵S-labeled forms of Vpr were detected as described in Materials and Methods and are indicated with arrows.