Inhibitor of DNA replication that promotes cell death in response to DNA damage. Acts as a guardian of the genome by killing cells with defective replication. Persistently blocks stressed replication forks by opening chromatin across replication initiation sites at stressed replication forks, possibly leading to unwind DNA ahead of the MCM helicase and block fork progression, ultimately leading to cell death. Acts independently of ATR. Also acts as an interferon (IFN)-induced antiviral protein which acts as an inhibitor of retrovirus protein synthesis. Specifically abrogates the production of retroviruses such as human immunodeficiency virus 1 (HIV-1) by acting as a specific inhibitor of the synthesis of retroviruses encoded proteins in a codon-usage-dependent manner. Binds to tRNAs and exploits the unique viral codon bias towards A/T nucleotides. The exact inhibition mechanism is unclear: may either sequester tRNAs, prevent their maturation via post-transcriptional processing or may accelerate their deacylation. Does not inhibit reverse transcription, integration or production and nuclear export of viral RNA.