Recombinant Human Double-stranded RNA-specific adenosine deaminase (ADAR), partial

Function

Catalyzes the hydrolytic deamination of adenosine to inosine in double-stranded RNA (dsRNA) referred to as A-to-I RNA editing (PubMed:12618436, PubMed:7565688, PubMed:7972084). 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 since the translational machinery read the inosine as a guanosine; 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 (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-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 (HCV), vesicular stomatitis virus (VSV), measles virus (MV), hepatitis delta virus (HDV), and human immunodeficiency virus type 1 (HIV-1). Exhibits either a proviral (HDV, MV, VSV and HIV-1) or an antiviral effect (HCV) and this can be editing-dependent (HDV and HCV), editing-independent (VSV and MV) or both (HIV-1). 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 (W) codon that permits synthesis of the large delta antigen (L-HDAg) which has a key role in the assembly of viral particles. However, high levels of ADAR1 inhibit HDV replication

Subcellular Location

Cytoplasm; Nucleus; Nucleus, nucleolus

Disease Association

Dyschromatosis symmetrica hereditaria (DSH) : An autosomal dominant pigmentary genodermatosis characterized by a mixture of hyperpigmented and hypopigmented macules distributed on the face and the dorsal parts of the hands and feet, that appear in infancy or early childhood. [The disease is caused by variants affecting the gene represented in this entry] | Aicardi-Goutieres syndrome 6 (AGS6) : A form of Aicardi-Goutieres syndrome, a genetically heterogeneous disease characterized by cerebral atrophy, leukoencephalopathy, intracranial calcifications, chronic cerebrospinal fluid (CSF) lymphocytosis, increased CSF alpha-interferon, and negative serologic investigations for common prenatal infection. Clinical features as thrombocytopenia, hepatosplenomegaly and elevated hepatic transaminases along with intermittent fever may erroneously suggest an infective process. Severe neurological dysfunctions manifest in infancy as progressive microcephaly, spasticity, dystonic posturing and profound psychomotor retardation. Death often occurs in early childhood. [The disease is caused by variants affecting the gene represented in this entry]

Tissue Specificity

Ubiquitously expressed, highest levels were found in brain and lung (PubMed:7972084). Isoform 5 is expressed at higher levels in astrocytomas as compared to normal brain tissue and expression increases strikingly with the severity of the tumor, being higher in the most aggressive tumors

Subunit

Homodimer. Homodimerization is essential for its catalytic activity (PubMed:12618436). Isoform 5 can form heterodimers with ADARB1/ADAR2. Isoform 1 interacts with ILF2/NF45 and ILF3/NF90 (PubMed:16055709). Binding to ILF3/NF90 up-regulates ILF3-mediated gene expression. Isoform 1 and isoform 5 (via DRBM 3 domain) interact with TNPO1 (PubMed:19124606, PubMed:24753571). Isoform 5 (via DRBM domains) interacts with XPO5 (PubMed:19124606). Isoform 1 and isoform 5 can interact with EIF2AK2/PKR and UPF1 (PubMed:17079286, PubMed:18362360)

• Kim U. et al. Molecular cloning of cDNA for double-stranded RNA adenosine deaminase, a candidate enzyme for nuclear RNA editing. — Proc. Natl. Acad. Sci. U.S.A. (1994)
• Patterson J.B. et al. Expression and regulation by interferon of a double-stranded-RNA-specific adenosine deaminase from human cells: evidence for two forms of the deaminase. — Mol. Cell. Biol. (1995)
• Liu Y. et al. Functionally distinct double-stranded RNA-binding domains associated with alternative splice site variants of the interferon-inducible double-stranded RNA-specific adenosine deaminase. — J. Biol. Chem. (1997)
• Deblandre G. et al. The gene coding for the interferon-inducible human dsRNA adenosine deaminase is transcribed into several messengers specifying different proteins. (JUN-)
• Bechtel S. et al. The full-ORF clone resource of the German cDNA consortium. — BMC Genomics (2007)
• Gregory S.G. et al. The DNA sequence and biological annotation of human chromosome 1. — Nature (2006)
• Mural R.J. et al. PubMed: CI-5GBD0VIIJ7C63 (SEP-)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)