Description
Catalyzes the hydrolytic deamination of adenosine to inosine in double-stranded RNA referred to as A-to-I RNA editing. This may affect gene expression and function in a number of ways that include mRNA translation by changing codons and hence the amino acid sequence of proteins; pre-mRNA splicing by altering splice site recognition sequences; RNA stability by changing sequences involved in nuclease recognition; genetic stability in the case of RNA virus genomes by changing sequences during viral RNA replication; and RNA structure-dependent activities such as microRNA production or targeting or protein-RNA interactions. Can edit both viral and cellular RNAs and can edit RNAs at multiple sites or at specific sites. Its cellular RNA substrates include: bladder cancer-associated protein, neurotransmitter receptors for glutamate and serotonin and GABA receptor. Site-specific RNA editing of transcripts encoding these proteins results in amino acid substitutions which consequently alters their functional activities. Exhibits low-level editing at the GRIA2 Q/R site, but edits efficiently at the R/G site and HOTSPOT1. Its viral RNA substrates include: hepatitis C virus, vesicular stomatitis virus, measles virus, hepatitis delta virus, and human immunodeficiency virus type 1. Exhibits either a proviral or an antiviral effect and this can be editing-dependent, editing-independent or both. Impairs HCV replication via RNA editing at multiple sites. Enhances the replication of MV, VSV and HIV-1 through an editing-independent mechanism via suppression of EIF2AK2/PKR activation and function. Stimulates both the release and infectivity of HIV-1 viral particles by an editing-dependent mechanism where it associates with viral RNAs and edits adenosines in the 5'UTR and the Rev and Tat coding sequence. Can enhance viral replication of HDV via A-to-I editing at a site designated as amber/W, thereby changing an UAG amber stop codon to an UIG tryptophan codon that permits synthesis of the large delta antigen which has a key role in the assembly of viral particles. However, high levels of ADAR1 inhibit HDV replication