Figure 4

HERC5 inhibits an early stage of Gag assembly at the plasma membrane. A, Schematic diagram of HIV-1 Gag assembly, budding and release at the plasma membrane. step I, Gag accumulates at the plasma membrane; step II, distortion of plasma membrane curvature; step III, increased distortion of the plasma membrane and formation of the "lollipop structure;" step IV, virion detaches its membrane from the host cell, undergoes proteolytic processing of Gag and remains closely associated with the host cell; step V virion distances itself from the host cell. B, Transmission electron micrographs of U2OS cells that were mock transfected ("mock"), transfected with pGag and empty vector ("-HERC5"), or co-transfected with pGag and pHERC5 + CS ("HERC5 + CS"). Scale bars = 500 nm. C, Transmission electron micrographs of U2OS cells that were mock transfected ("mock"), transfected with pR9 and empty vector ("-HERC5"), or co-transfected with pR9 and pHERC5 + CS ("HERC5 + CS"). Scale bars = 300 nm. D, Transmission electron micrographs of U2OS cells that were transfected as described in parts B and C showing immunogold labeling of p24CA (Gag). Gold particles are 10 nm in size. Bottom panels of the micrographs are zoomed images of the white boxes in the upper panels. Scale bars = 100 nm. N, nucleus; C, cytoplasm; O, outside of cell.