Figure 3.

The function of RanBP2-mediated sumoylation of TRIM5α in HIV-1 infection

The envelope glycoprotein (Env) mediates human immunodeficiency virus type 1 (HIV-1) fusion with the cell membrane. The HIV-1 core consists of the capsid (CA) protein and its contents. The capsid proteins surround two copies of the RNA genome and proteins, such as reverse transcriptase and integrase. Before or during capsid disassembly, which is necessary for nuclear import of the viral genome, TRIM5α blocks retroviral infection by intercepting capsids before they reach the nucleus and promotes premature disassembly. The E3 SUMO ligase RanBP2 is associated with Ubc9 and sumoylated RanGAP1 at cytoplasmic filaments of nuclear pore complexes (NPCs). RanBP2 promotes sumoylation of TRIM5α in the cytoplasm, resulting in its proper localization and antiviral activity.