Fig. 3.

Vpr recruits the DDB1-Cul4A E3 ubiquitin ligase to target UNG2 for proteasomal degradation. (A) 293T cells were cotransfected with HA-UNG2 expression vector and empty vector, Vpr, or L64P Vpr expression vector. UNG2, Vpr, and tubulin in cell lysates were detected on an immunoblot. (B) DDB1 was knocked down with siRNA. The cells were then transfected with Vpr and UNG2 expression vector. UNG2, Vpr, DDB1, and tubulin were detected on an immunoblot. (C) Cul4 was knocked down in 293T cells. The cells were then transfected with Vpr and UNG2 expression vector. UNG2, Vpr, Cul4A, and tubulin were detected on an immunoblot. (D) 293T cells were cotransfected with UNG2, Vpr, or empty expression vector and myc-DDB1 or W561A myc-DDB1 expression vector. UNG2, Vpr, and DDB1 in the cell lysates were detected on an immunoblot.