HIV enzymes: reverse transcriptase, integrase, and protease

During infection by HIV, three enzymes play essential roles in the life cycle of the virus. Reverse transcriptase (orange, top; PDB ID 3V4I) copies the viral RNA genome and makes a DNA copy. Integrase (magenta, middle, PDB ID 3oya) inserts the viral DNA into the cell's DNA. In the last steps of the virus life cycle, HIV protease (blue, bottom, PDB ID 1kj4) cuts HIV proteins into their functional parts.