LTR (Long Terminal Repeat)

Long Terminal Repeats (LTRs) are repeated DNA sequences found at both ends of certain genetic elements called retrotransposons and some viruses like HIV. They act as regulatory regions, controlling the activity of these elements—such as when they copy and insert themselves into the genome. LTRs contain signals for initiating transcription, which is the process of making RNA from DNA. They also help integrate the element into new locations within the DNA. In essence, LTRs are crucial for the lifecycle of these mobile genetic elements, enabling their replication and spread within the genome.