HIV reverse transcription enzyme. Molecular models of the reverse transcriptase enzyme found in HIV (the human immunodeficiency virus). The foreground model shows the helices and arrowed sheets representing the enzyme's shape (secondary structure). The background model shows the 7844 atoms (spheres) of the molecular structure. Reverse transcriptase is an enzyme that is a key part of the process of producing DNA (deoxyribonucleic acid) from the instructions contained in a strand of RNA (ribonucleic acid). Many viruses, including HIV, consist of a core of RNA, and this reverse transcription is how HIV infects human cells. This enzyme is from the HIV-1 form of HIV, the virus that causes AIDS (acquired immune deficiency syndrome).