{"uniprot":"Q8NCV1","gene":"ADAD2","name":"Adenosine deaminase domain-containing protein 2","organism":"Homo sapiens (Human)","status":"dark","length":583,"sequence":"MASASQGADDDGSRRKPRLAASLQISPQPRPWRPLPAQAQSAWGPAPAPATYRAEGGWPQVSVLRDSGPGAGAGVGELGAARAWENLGEQMGKAPRVPVPPAGLSLPLKDPPASQAVSLLTEYAASLGIFLLFREDQPPGPCFPFSVSAELDGVVCPAGTANSKTEAKQQAALSALCYIRSQLENPESPQTSSRPPLAPLSVENILTHEQRCAALVSAGFDLLLDERSPYWACKGTVAGVILEREIPRARGHVKEIYKLVALGTGSSCCAGWLEFSGQQLHDCHGLVIARRALLRFLFRQLLLATQGGPKGKEQSVLAPQPGPGPPFTLKPRVFLHLYISNTPKGAARDIYLPPTSEGGLPHSPPMRLQAHVLGQLKPVCYVAPSLCDTHVGCLSASDKLARWAVLGLGGALLAHLVSPLYSTSLILADSCHDPPTLSRAIHTRPCLDSVLGPCLPPPYVRTALHLFAGPPVAPSEPTPDTCRGLSLNWSLGDPGIEVVDVATGRVKANAALGPPSRLCKASFLRAFHQAARAVGKPYLLALKTYEAAKAGPYQEARRQLSLLLDQQGLGAWPSKPLVGKFRN","function_summary":"A nuclear RNA-processing enzyme that couples a double-stranded RNA-binding module to a catalytic deaminase/editase core to modulate adenosine-containing nucleic acids. By binding structured RNAs and assembling with processing factors, it promotes RNA maturation pathways—particularly steps in tRNA processing—within nucleolar and nucleoplasmic hubs, with a soluble pool detectable in the cytosol. Its mechanism centers on dsRNA-guided substrate capture followed by hydrolytic deamination that tunes RNA quality and function.","plain_language":"ADAD2 has barely been studied. The model's best guess: A nuclear RNA-processing enzyme that couples a double-stranded RNA-binding module to a catalytic deaminase/editase core to modulate adenosine-containing nucleic acids. By binding structured RNAs and assembling with processing factors, it promotes RNA maturation pathways—particularly steps in tRNA processing—within nucleolar and nucleoplasmic hubs, with a soluble pool detectable in the cytosol.","uniprot_summary":"Probable adenosine deaminase.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"},{"id":"GO:0003723","label":"RNA binding"},{"id":"GO:0004000","label":"adenosine deaminase activity"}],"biological_process":[{"id":"GO:0008033","label":"tRNA processing"}],"cellular_component":[{"id":"GO:0005829","label":"cytosol"},{"id":"GO:0005654","label":"nucleoplasm"},{"id":"GO:0005730","label":"nucleolus"}]},"interpro":[{"id":"IPR044454","name":"ADAD2, double-stranded RNA binding domain","type":"domain","start":112,"end":179},{"id":"IPR014720","name":"Double-stranded RNA-binding domain","type":"domain","start":115,"end":181},{"id":"IPR002466","name":"Adenosine deaminase/editase","type":"domain","start":207,"end":582}],"reasoning":"I begin with the domain architecture. The N-terminal half carries two overlapping double-stranded RNA-binding domain signatures: IPR044454 (ADAD2, double-stranded RNA binding domain, residues 112–179) and IPR014720 (Double-stranded RNA-binding domain, residues 115–181). This tandem annotation pinpoints a canonical dsRBD fold that recognizes A-form RNA helices and structured RNAs, typically guiding RNA-processing assemblies in the nucleus and nucleolus. The C-terminal half is dominated by IPR002466 (Adenosine deaminase/editase, residues 207–582), a metallo-dependent deaminase/editase core that catalyzes hydrolytic deamination of adenosine to inosine in diverse nucleic acid contexts. The ordered layout—an N-terminal dsRNA-binding module feeding substrate selection into a C-terminal deaminase/editase engine—creates a targeting-and-catalysis machine: the dsRBD recruits structured RNA or nucleic-acid substrates, while the deaminase core executes adenosine deaminase chemistry.\n\nThis architecture dictates molecular function. The dsRBD confers high-affinity RNA binding, aligning with GO:0003723 RNA binding. The extensive editase/deaminase core establishes GO:0004000 adenosine deaminase activity, enabling hydrolytic removal of amino groups from adenosine residues. The presence of a sizable modular scaffold and the need to assemble with RNA-processing partners further supports GO:0005515 protein binding, reflecting multivalent interactions required for assembly and regulation.\n\nFrom function to process, the coupling of dsRNA recognition and deamination naturally feeds into RNA maturation pathways. The deaminase/editase domain is classically wired into RNA processing circuits, and the dsRBD targets structured precursors that transit the nucleolus and nucleoplasm. This causal chain places the protein in GO:0008033 tRNA processing, where adenosine-to-inosine editing and associated surveillance can modulate tRNA maturation and quality control.\n\nCellular location follows from the same logic. dsRBD-guided RNA processing and the editase chemistry concentrate in nuclear territories where ribosome biogenesis and RNA maturation occur. The nucleolus emerges as a primary hub for structured RNA handling and tRNA/pre-tRNA trafficking, consistent with GO:0005730 nucleolus. Dynamic RNA-processing assemblies also operate in the GO:0005654 nucleoplasm and soluble nuclear subcompartments, with shuttling pools detectable in the GO:0005829 cytosol as RNA-processing factors traffic between compartments.\n\nMechanistically, I hypothesize that the dsRBD module captures structured RNA substrates and adaptor RNAs, positioning them for catalytic editing by the deaminase/editase core. This causes localized adenosine deamination that fine-tunes RNA maturation and possibly nucleic-acid surveillance. Likely interaction partners include nucleolar RNA-binding proteins and processing factors that cohabit these hubs—such as nucleolin and fibrillarin for ribonucleoprotein assembly, DDX-family RNA helicases for remodeling, and tRNA maturation enzymes—together forming a modular complex that coordinates RNA processing within the nucleus and nucleolus.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q8NCV1.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q8NCV1"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q8NCV1/entry","atlas":"/p/Q8NCV1"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}