Subcellular distribution of ADAR1 isoforms is synergistically determined by three nuclear discrimination signals and a regulatory motif.
ADAR1 is an RNA-specific adenosine deaminase that edits RNA sequences. We have demonstrated previously that different ADAR1 isoforms are induced during acute inflammation. Here we show that the mouse ADAR1 isoforms are differentially localized in cellular compartments and that their localization is controlled by several independent signals. Nuclear import of the full-length ADAR1 is predominantly regulated by a nuclear localization signal at the C terminus (NLS-c), which consists of a bipartite basic amino acid motif plus the last 39 residues of ADAR1. Deletion of the NLS-c causes the truncated ADAR1 protein to be retained in the cytoplasm. The addition of this sequence to pyruvate kinase causes the cytoplasmic protein to be localized within the nucleus. The localization of nuclear ADAR1 is determined by a dynamic balance between the nucleolar binding activity of the nucleolar localization signal (NoLS) in the middle of the protein and the exporting activity of the nuclear exporter signal (NES) near the N terminus. The NoLS consists of a typical monopartite cluster of basic residues followed by the third double-stranded RNA-binding domain. These signals act independently; however, NES function can be completely silenced by the NLS-c when a regulatory motif within the catalytic domain and the NoLS are deleted. Thus, the intracellular distribution of the various ADAR1 isoforms is determined by NLS-c, NES, NoLS, and a regulatory motif.
Nie
Yongzhan
Y
Department of Surgery, Yale University School of Medicine, New Haven, CT 06520, USA.
Zhao
Qingchuan
Q
Su
Yingjun
Y
Yang
Jing-Hua
JH
D000243:Adenosine Deaminase / Q000096:biosynthesis* / Q000737:chemistry*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D017353:Gene Deletion; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D005231:Fatty Acids, Unsaturated; D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase; C038753:leptomycin B