Catalyzes the hydrolytic deamination of adenosine to inosinein double-stranded RNA (dsRNA) referred to as A-to-I RNA editing. This may affect geneexpression and function in a number of ways that include mRNAtranslation by changing codons and hence the amino acid sequence ofproteins since the translational machinery read the inosine as aguanosine; pre-mRNA splicing by altering splice site recognitionsequences; RNA stability by changing sequences involved in nucleaserecognition; genetic stability in the case of RNA virus genomes bychanging sequences during viral RNA replication; and RNA structure-dependent activities such as microRNA production or targeting orprotein-RNA interactions. Can edit both viral and cellular RNAs and canedit RNAs at multiple sites (hyper-editing) or at specific sites (site-specific editing). Its cellular RNA substrates include: bladder cancer-associated protein (BLCAP), neurotransmitter receptors for glutamate (GRIA2) and serotonin (HTR2C) and GABA receptor (GABRA3). Site-specificRNA editing of transcripts encoding these proteins results in aminoacid substitutions which consequently alters their functionalactivities. Exhibits low-level editing at the GRIA2 Q/R site, but editsefficiently at the R/G site and HOTSPOT1. Its viral RNA substratesinclude: hepatitis C virus (HCV), vesicular stomatitis virus (VSV), measles virus (MV), hepatitis delta virus (HDV), and humanimmunodeficiency virus type 1 (HIV-1). Exhibits either a proviral (HDV, MV, VSV and HIV-1) or an antiviral effect (HCV) and this can beediting-dependent (HDV and HCV), editing-independent (VSV and MV) orboth (HIV-1). Impairs HCV replication via RNA editing at multiplesites. Enhances the replication of MV, VSV and HIV-1 through anediting-independent mechanism via suppression of EIF2AK2/PKR activationand function. Stimulates both the release and infectivity of HIV-1viral particles by an editing-dependent mechanism where it associateswith viral RNAs and edits adenosines in the 5'UTR and the Rev and Tatcoding sequence. Can enhance viral replication of HDV via A-to-Iediting at a site designated as amber/W, thereby changing an UAG amberstop codon to an UIG tryptophan (W) codon that permits synthesis of thelarge delta antigen (L-HDAg) which has a key role in the assembly ofviral particles. However, high levels of ADAR1 inhibit HDV replication. [1-14]

MNPRQGYSLSGYYTHPFQGYEHRQLRYQQPGPGSSPSSFLLKQIEFLKGQLPEAPVIGKQTPSLPPSLPGLRPRFPVLLASSTRGRQVDIRGVPRGVHLRSQGLQRGFQHPSPRGRSLPQRGVDCLSSHFQELSIYQDQEQRILKFLEELGEGKATTAHDLSGKLGTPKKEINRVLYSLAKKGKLQKEAGTPPLWKIAVSTQAWNQHSGVVRPDGHSQGAPNSDPSLEPEDRNSTSVSEDLLEPFIAVSAQAWNQHSGVVRPDSHSQGSPNSDPGLEPEDSNSTSALEDPLEFLDMAEIKEKICDYLFNVSDSSALNLAKNIGLTKARDINAVLIDMERQGDVYRQGTTPPIWHLTDKKRERMQIKRNTNSVPETAPAAIPETKRNAEFLTCNIPTSNASNNMVTTEKVENGQEPVIKLENRQEARPEPARLKPPVHYNGPSKAGYVDFENGQWATDDIPDDLNSIRAAPGEFRAIMEMPSFYSHGLPRCSPYKKLTECQLKNPISGLLEYAQFASQTCEFNMIEQSGPPHEPRFKFQVVINGREFPPAEAGSKKVAKQDAAMKAMTILLEEAKAKDSGKSEESSHYSTEKESEKTAESQTPTPSATSFFSGKSPVTTLLECMHKLGNSCEFRLLSKEGPAHEPKFQYCVAVGAQTFPSVSAPSKKVAKQMAAEEAMKALHGEATNSMASDNQPEGMISESLDNLESMMPNKVRKIGELVRYLNTNPVGGLLEYARSHGFAAEFKLVDQSGPPHEPKFVYQAKVGGRWFPAVCAHSKKQGKQEAADAALRVLIGENEKAERMGFTEVTPVTGASLRRTMLLLSRSPEAQPKTLPLTGSTFHDQIAMLSHRCFNTLTNSFQPSLLGRKILAAIIMKKDSEDMGVVVSLGTGNRCVKGDSLSLKGETVNDCHAEIISRRGFIRFLYSELMKYNSQTAKDSIFEPAKGGEKLQIKKTVSFHLYISTAPCGDGALFDKSCSDRAMESTESRHYPVFENPKQGKLRTKVENGEGTIPVESSDIVPTWDGIRLGERLRTMSCSDKILRWNVLGLQGALLTHFLQPIYLKSVTLGYLFSQGHLTRAICCRVTRDGSAFEDGLRHPFIVNHPKVGRVSIYDSKRQSGKTKETSVNWCLADGYDLEILDGTRGTVDGPRNELSRVSKKNIFLLFKKLCSFRYRRDLLRLSYGEAKKAARDYETAKNYFKKGLKDMGYGNWISKPQEEKNFYLCPV