Vif induces an early G1-to-S transition that is Cul5 independent. (A) HeLa cells were transfected with pcDNA, wild-type Vif, or the Vif mutant SLQ, and the proportion of cells in S phase at time 0 and 3 hours after release from cell-cycle synchronization after treatment with BrdU/7AAD was determined. Vertical axes show the number of cells that incorporated BrdU. Horizontal axes show total DNA content by 7AAD staining. The top small box in each plot denotes the cell number at the S phase of the cell cycle, while the lower small box denotes the cells at G1. The calculated S/G1 ratio is noted in the upper right of each plot. (B) Combined results from multiple experiments of the type shown in panel A. Vertical axis denotes the ratio of the number of cells in the S phase to the number of cells in G1. The SLQ mutants fail to interact with the Cul5-ElongB/C E3 ligase complex. *P < .05 for bar 2 vs bar 1. The mean ± SE of 3 experiments is shown.
