Double-Stranded RNA-Specific Adenosine Deaminase: Nucleic Acid Binding Properties

Abstract The RNA-specific adenosine deaminase (ADAR1, herein referred to as ADAR) is an interferon-inducible RNA-editing enzyme. ADAR catalyzes the C-6 deamination of adenosine in double-stranded (ds) structures present in viral RNAs and cellular pre-mRNAs as well as synthetic dsRNA substrates. ADAR possesses three functionally distinct copies of the highly conserved double-stranded RNA binding R motif (R I , R II , R III ) implicated in the recognition of dsRNA structures within the substrate RNAs. ADAR is also a Z-DNA-binding protein. Two Z-DNA binding motifs (Zα and Zβ) present in ADAR correspond to repeated regions homologous to the N-terminal region of the vaccinia virus E3L protein. Here we describe assay methods for measurement of ADAR enzymatic activity, dsRNA binding activity, and Z-DNA binding activity.