HIV reverse transcription enzyme. Molecular model of the reverse transcriptase enzyme found in HIV (the human immunodeficiency virus). The model shows the helices and arrowed sheets representing the enzyme's shape (secondary 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). This is the reverse of the RNA from DNA process. 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). This model is of the unliganded form of the HIV-1 reverse transcriptase enzyme.